SRT is a simpler target
Basic SubRip has numbered cues, time ranges and text. Some WebVTT cue settings have no direct equivalent.
Cue numbering is regenerated
SRT indexes are output in playback order rather than trusting arbitrary source IDs.
Do not flatten warnings silently
When VTT contains settings that SRT cannot preserve, the converter reports the limitation instead of pretending perfect equivalence.
Review line breaks
Different players wrap captions differently. Keep deliberate line breaks and test on the target screen size.