Hello, could you tell us something about how to record samples for English vocals?
As far as I am aware, Synthesizer V does not support recording samples or any aspect of voicebank creation as of right now. If you wish to create a voicebank a different program called UTAU allows you to create your own voicebank. I personally would not recommend it because sound and just general quality is significantly worse than SynthV. That said, if you know your stuff you could create a high quality voice bank in UTAU that’s just as good as SynthV.
DeepVocal also allows creating your own voicebanks.