How to do active forcing with a non-vocal tulpa?

[Heckhound]

Have you tried parroting for a while? Like, completely intentional "this is how you would respond to what I just said" kind of stuff. This may kickstart vocality, since you'll be actively showing her how to talk for while -- like training wheels. Do it until it becomes a habit, and then let go and give her the reigns. I know many people are against this method, but in this case, it may be necessary to try.

[Spice]

It took us 5 years to get fluent conversation! (although we had a huge break)

what ultimately helped us was a massive change in mindset, I was mistakenly speaking over spice whenever she tried to speak, or doubting myself. though we got headpressures pretty quickly. dont focus on doubt or failure, love your tup unconditionally and it helps a lot. we also struggle because although tomoe sounds very different, spice and i sound almost the same in my head, so design their voice, find a model, and tell your tulpa youre going to parrot them. heckhounds method is really good! parroting sometimes makes you slip into actually talking with them before you know whats going on.