Don't let malware ruin your love for SoundFonts. Respect the developer, support the music, and leave the sketchy repacks in the digital dustbin of history.
If you’re the legitimate owner of the app and need help with installation, backup, or sideloading (e.g., using AltStore, SideStore, or a developer certificate), I can explain those general methods without encouraging repacking or cracking.
Disclaimer: This information is for educational and preservation purposes. Piracy of actively sold software harms developers. However, since the Bismark BS16i is officially abandoned (no longer on the App Store) and will not run on modern iOS without modification, the preservation community views repacks as archival.
Do you have a specific you're trying to load, or