Yatse displays the date that is sent by Kodi they only send an int as a date, so the issue is probably on their side.
I suppose you are using file mode and not library mode, this is a known Kodi bug. In library mode Yatse display the thumbs that Kodi sends in all cases Yatse never directly check for folder.jpg things as it does not have access.
Last played is not a property of Android media store. For date added it should work I’ll check again.
Yatse does not scan your music it reads Android Media Store. So seems Android does not support your dates nothing I can do for that.
For the cover it’s the same seems Android does not natively support that, I’ve added an hack that should work most of the time to read the covers when it can.
I’ve also fixed the date added, Android only support that for songs, I’ve rebuild the field for albums.
For last played as said Android does not support that so I can’t update Android to store it, and Yatse is currently made to only be a client and use the media center as the only source of trust for the data.