I’ve found a few posts about metadata search limitations, namely in anime shows, describing similar limitations when using Infuse (in my case the macOS version).
My suggestion is to implement online metadata search similarly to how NOVA Player (Android) works.
Regardless of the folder structure, file naming, nfo files, artwork file format, instead of trying to override metadata, which in some scenarios is cumbersome or not even possible, the user can manually search for online metadata for each episode / file by specifying the show name, season and episode (e.g. One Piece s01e01).
As is, if the file naming structure doesn’t follow the required format, the metadata search seems to assume the file is a movie, not a serialized tv show. In situations where the folder structure can be updated to follow the standard, but for technical reasons the file name itself can’t be changed, even my manually creating metadata and artwork (e.g. MediaElch) Infuse still doesn’t display the metadata 100% correctly and it even seems not to be able to scrobble to Trackt.tv