Thanks for the feedback, as I’m glad it works for you now!
In regards to actor images, adding an option to ignore them is totally possible. It just needs to be prioritized and added to the backlog. The reason why images are mirrored for each folder is due to technical limitations. Actor images must be found locally or be specified by a fully qualified path. Since there is no way to guarantee the location where people choose to store such information, locally is the best option. In addition, since actor images are limited to head shots, the disk space requirement for them is quite low.
As for the “JAV” genre tag, this is important for other edge-cases. For example, many users have collections that include JAV, but are not exclusively all JAV. So when adding a small amount of JAV content to their libraries, having accurate genre tags is desirable for searching.
In regards to thumbnail files, indeed some of the metadata included is exclusive to KODI standards. While this information might take up a marginal amount of disk space, since KODI has been the most dominant and popular open source media center project for a while it makes sense to align compatibility with it. This is especially true, since other projects tend to use subsets from the KODI specification, meaning general compatibility can be maintained.
I hope this clarifies things a bit! (^_^);