I've figured out a way to use an Elgato Stream Deck with VEGAS Stream, leveraging BarRaider's Super Macro Stream Deck plugin. Here's how you can create a Stream Deck profile for use with any of your VEGAS Stream collections.

1. Install BarRaider's SuperMacro plugin from the Elgato store within the Stream Deck software.
2. Duplicate the default Stream Deck profile and rename the copy to match your collection, e.g., "VEGAS Stream - Cubic".
3. Switch to the new profile, if it's not already showing on your Stream Deck.
4. Launch VEGAS Stream and, for the examples below, open the default "Cubic Collection".
5. Resize the VEGAS Stream window somewhere on your screen that allows you to see it, but where it won't show up while you're streaming - maybe to the left of the screen or on an extended monitor if your streaming from one of two that you have on your PC. You can also resize it to take up less screen real estate.

The way this works is by capturing and playing back the mouse location from a predictable place on the VEGAS Stream interface, which allows the macro to then Arrow Down and Tab a predictable number of times to select a graphic or transition and play it in (or out) using CTRL and Spacebar keyboard commands.

First, the mouse position needs to be captured. To do this, drag a "Super Macro" action from the "Super Macro [BarRaider]" menu in the Stream Deck software plugin menu, place it on the top left button, and then put this into the "Short-Press Macro" field:

{{MSAVEPOS}}

You can also make the Title text say something, like "Start", and change the icon to something else, like a a power button from the Stream Deck Icon Library for example (there is a screenshot below showing how I built my Cubic Collection profile, for reference).

Here's the important part, which will help ensure that the next steps will succeed. Place the mouse cursor directly over the Cubic Collection "Text Transition" in the VEGAS Stream window and press the "Start" button on the Steam Deck. This will capture that mouse position and serve as the starting point for each of the upcoming macro actions.

Next, drag a "Super Macro Toggle" action to the button next to "Start" in the Stream Deck software, make the Title "Main", and add this in the "Primary Macro" field:

{{MLOADPOS}}{{MLEFTDBLCLICK}}
{{ArrowDown}}
{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}
{{CTRL}{SPACE}}

Here's what this does. When the "Main" button on the Stream Deck is pressed, this will load the mouse position that was captured with the "Start" button, Arrow Down once, Tab nine (9) times, and then use CTRL and Spacebar keyboard shortcuts to play-in the selected graphic which, in this case, is the "Main Title" graphic from the Cubic Collection.

Important Note: Regardless of where the mouse cursor was when you pressed the "Main" button, the cursor will jump back to the starting point (the "Text Transition") and bring the VEGAS Stream window into focus, before playing-in the graphic. So, at absolute minimum, the "Text Transition" needs to be visible on your desktop, otherwise the macro will produce unpredictable (or no) results.    

Now, in the "Secondary Macro" field of the "Main" Super Macro Toggle action, add the same macro commands:

{{MLOADPOS}}{{MLEFTDBLCLICK}}
{{ArrowDown}}
{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}
{{CTRL}{SPACE}}

This allows you to then press the "Main" button on the Stream Deck a second time, and the "Main Title" graphic will play-out. You can move the mouse around while the graphic is playing, but don't cover the "Text Transition" on the VEGAS Stream window because the mouse needs to be able to jump back to this starting position so that it can execute the macro commands properly.  

That's it...now you can build an entire Stream Deck profile for the VEGAS Stream Cubic Collection (or any other one), by following the same pattern!  For example, as a next step, drag a "Super Macro Toggle" action to the button next to "Main" in the Stream Deck software, make the Title "M Head" (for "Main Header", which is the second graphic in the Cubic Collection) and add this in the "Primary Macro" field:

{{MLOADPOS}}{{MLEFTDBLCLICK}}
{{ArrowDown}}
{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}
{{CTRL}{SPACE}}

Note that this "Primary Macro" is the same as the "Main" one, except that it Tab's ten (10) times, instead of nine. The "Secondary Macro" field for the "M Head" button is exactly the same as the "Primary Macro" - and the same is true of any additional Super Macro Toggle actions that you create, for example:

{{MLOADPOS}}{{MLEFTDBLCLICK}}
{{ArrowDown}}
{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}{{Tab}}
{{CTRL}{SPACE}}

Following on...you can create another Super Macro Toggle for the "Bug" graphic the same way, but with eleven (11) Tab's...and so on.

Here are a few things to keep in mind about this solution:
1. It may take a little getting used to having the mouse jump back to the VEGAS Stream window on Stream Deck key press, but it's not too distracting (IMO). Also, remember to use the "Start" button to capture the mouse position over the "Text Transition" (or whichever you use from your collection), at the start of each session. This only needs to be done once per session, unless you move the VEGAS Stream window around after having set it. It's also important to understand that the number of {{Tab}} commands (and, potentially {{ArrowDown}} commands) in each macro directly correlates to the number of items, such as graphics and transitions, in the collection - and the collection item that use use as a starting point. So, if your collection is larger or smaller than the Cubic Collection in the example above, or if you record the mouse over a different graphic or transition, the number of commands will need to be adjusted accordingly in the macros. Once you work out the correct number to successfully play-in the first graphic in the collection from the desired starting point though, the pattern should be the same for all other Stream Deck key macros that you create for the collection (i.e., {{Tab}}+1).
2. The default gear icons in the Super Macro Toggle can be changed to a Primary Image and Secondary Image within the macro if you'd like to, say, make the primary a stop icon and the secondary a play icon from the Stream Deck Icon Library (or even make you own, like the ones I created in the screenshot below where the "Bullet" graphic is playing). If you save the Stream Deck profile though, the custom icons won't be included so when the profile is re-installed they'll be the default gears again. However, if you just leave the default gear icons on the Stream Deck keys, the little green gear on the lower right will toggle to the bigger gear on the lower left, to serve as an indication of which key is currently playing.
3. While you can select (and de-select) a Transition using this method, you'll still need to click on the Live Video Input (i.e., your camera or display) to actually transition to it - (see below for an update on this!). Also, if you play in a graphic or transition without having played the previous one out, you may have unpredictable results (unless that's what you're going for!). 😁
4. If, "of course, this is where it all falls down" and you just want to delete the profile you created, navigate to Preferences in the Stream Deck software, go to the Profiles tab, select the profile and click the minus sign below it. If you want to then delete Super Macro (i.e., the "Don't Panic" button failed too), right click on any of the six actions under "Super Macro [BarRaider]" in the Stream Deck software, select "Uninstall", and you'll be back on "Magrathea...in the great and glorious days". 😋

Please post any questions you have to this thread and I'll do my best to help you set up a profile that works!

PS: If you figure out a more elegant way to integrate VEGAS Stream and Elgato Stream Deck, please share!!

G