Thank you so much for such a lovely and detailed review! I’m really happy to hear that you enjoyed the demo so much. ^^
And thank you for taking the time to report the technical issues as well!
Regarding the save/import problem and the database warnings, my guess is that the two issues may actually be connected. The web version of Ren’Py handles saves differently from the downloadable build, and it isn’t really designed around importing external save files in the same way. Browser saves are handled through the browser’s own storage rather than as ordinary save files, so attempting to export and then import them may have caused the database issue you encountered, especially in Safari.
I haven’t encountered this particular problem during testing, but thank you very much for providing a screenshot! I’ll keep it in mind and see whether I can reproduce it.
As for the credits, there is actually a full credits section on the main game page. Most of the music for Sinful Testament is handled by LeMoon, although she doesn’t have an itch.io profile and isn’t really a public-facing creator.
The rest of the music and sound effects come from various stock libraries under CC0 licenses, including sources such as Freesound.
Everything else in the game, including the art, writing, and programming, is done by me personally. For the visual side, I mainly work in CLIP STUDIO PAINT, and I also purchase some licensed assets for design elements and backgrounds through the CLIP STUDIO ASSETS store and marketplaces such as ACON3D and similar sites.
And regarding development updates, I do occasionally post progress, new art, screenshots, and other development-related things on my X account:
I don’t currently maintain regular Dev Logs on itch.io, but I’m very happy to hear that you’d be interested in seeing more behind-the-scenes development content! I may consider posting more of that in the future. :3
Once again, thank you so much for playing and for leaving such a kind review. Calling yourself a fan of the game genuinely made me very happy. <3