Okay, looks like the “Sync Tempo” function isn’t detecting your DAW’s automation correctly (there are no tempo markers in the Time Axis). You can find information about manually adding tempo changes in SynthV Studio here:
Even if i change the tempo in SYNTHV (which is very difficult because i cant put it exactly where i want), when the projects changes the tempo, the playback of SYNTHV goes back a few ms, so it plays 2 times the first note where the tempo changes.
In that case try rendering a wav from SynthV Studio and dragging that into your DAW (and then mute the SynthV VST).
If it sounds good using the rendered wav, that would indicate a compatibility issue with the VST and your DAW.
If it still sounds wrong, then it would mean your tempo changes don’t match correctly (or that the tempo changes you’re trying to implement are not possible in SynthV Studio). SynthV Studio can only change tempo at quarter-measure intervals, which may not be suitable for some songs.