Edit speed of sprite or multiple objects in VSDC

[Coelophysis]

Greetings all.
I'm currently using VSDC 6.8 to add text to a video. (I'm not using the subtitles function because I would like the text to be in particular positions around the video, sometimes on multiple sides.)
Now I would need to slightly speed up the whole video + text complex. I see that it is possible to move around multiple objects as a whole by converting them into a sprite, which I've done. However, this does not allow changing their speed -- there is a "sprite wizard" function that allegedly allows to edit a sprite as a single object, but as far as I can tell it allows only to edit the transitions between its components.
Manually changing the length of the sprites on the timeline does not affect their speed; it simply removes pieces off them. Changing the speed of the video does not, of course, affect the text objects.
There is quite a lot of text, and if it's at all possible I'd really rather not write it all again, or change manually the onset and duration of each single text box. The only solution I can think of is to export the sprites as videos, re-import them into the timeline, and change their speed then. However, that seems to lead to considerable quality loss*.
This feels like it should be a simple issue, but I cannot find any other way around it. I'm starting to feel quite stupid, and I'd be grateful if anyone had any insight.


EDIT: * = I found a solution to the secondary problem, at least. It might not have been a quality loss in the imported video itself, but simply to the way it's visualized during editing. I got rid of that by looking at Options > Acceleration options > Proxy for preview & Proxy for export > making sure they're both "Original quality".