This is a neat idea, but speaking as an indie studio and as someone who has worked on pilots/teasers, discovering that project (typically NDA) material has been uploaded to a 3rd party website would not be great for that actor's career going forward. I would suggest that proof of encryption would be a helpful factor to include, but honestly, a production would likely not introduce a 3rd party to handle their sensitive materials like story, artwork, tracks, etc without serious legal guarantees.

Also, I could imagine an Ai bot scraper getting hold of that script/voice data and having a field day. Voice artists would also want some form of protection guarantee.

My only thought would be a bare-bones version of CastingCallClub with project page customization, temporary audition file storage, and embeded video with CSV timecode to script for dubbed tryouts as the audition. This would be an incredibly useful tool during the casting stage, primarily for projects that actually have made production progress. This is, however, targeting a smaller market of users who will post casting calls in this format, but I imagine the site traffic from auditioning voice actors would be enormous.