As I understand it currently, you can send an API request to HandyFeeling’s API that specifies the script location as on your local network; then it will attempt to download it from that location instead of you uploading it to their servers only for the Handy to download it again. While that works, it doesn’t solve any of the problems: you’re still reliant on their API even for local playback. The only real solution is hosting your own API server, but that won’t happen until they either make it available or someone reverse engineers it.
Until then, I’m trying to optimize my bluetooth script player to mitigate the command rate limitations as best as possible by interpolating high-resolution scripts to the command rate limit. While that loses a bit of haptic resolution, it’s a lot better than the stuttering you get if you attempt to play high-resolution scripts directly.