Regardless of the titler used for titling purposes, I'd just copy/paste the title and change the text in the copy - all the animations etc 'should' be retained. But as I don't use subtitles, I don't know if that aproach would work there.
@Jiri-Vlach Or you could use an effect like Picture in Picture, keyframe it, then click the fx+ button that will open the Plugin chooser & Save as, The Plugin chooser can be opened from the View - Window tab & docked to the UI where you can drag & drop the preset with it's keyframes still included,
Multiple effects can be added & saved in one preset, & it might be a good idea to add a time length to the name because a preset created in a 10 sec event won't show the keyframes correctly when added to a 5sec event, they're still there but you'd have to drag the 5sec event to make it 10sec to show all the keyframes, then adjust as needed.
@Jiri-Vlach This is a feature that many users here have been wanting for a while. The current way that Vegas handles text is honestly quite archaic in comparison to other NLE's available, very much a sore spot in their tool box that will hopefully be addressed with a new text and titles feature in an upcoming version of Vegas (Hopefully VP 22, but I haven't heard anything that sounded like they are actually addressing the text and titles in the next version)
Otherwise using the Protype Titler like @Dexcon suggested, or the P-n-P effect like @Gid suggested would be the next go to. If you were hoping for something more, the only real upgrade from those, at this time, would be to subscribe/buy a license for something like BorisFX and their Continuum Plugins. It looks like they have a pretty robust Titles and Motion graphics program but I can't say much to it as I've not gone that route.