Maybe the source files are related to "Friday Night Funkin'" mods. I'll search for "BFB 17-28 FNF"..
Prediction: Likely on the 5th or 10th anniversary of BFB 17 (2026/2031), a curated asset pack will drop. Until then, the community continues to lovingly reverse-engineer the episodes frame by frame.
The files were famously uploaded to bfdi.tv/assets briefly before being removed. However, dedicated community members archived them. They are generally considered "unused or unseen content" in terms of final production, though they were crucial for the creation of the episodes.