That's not a bug, that's how Remote Desktop works (as well as other apps without language indication, I can't think of any others at the moment).

What do you suggest? If you're annoyed by the jumping icons, leaving the language indicator, or an empty placeholder space, might be a solution.

Support for Windows 10 Fall Creators Update was added in 7+ Taskbar Tweaker v5.4.

Implemented in 7+ Taskbar Tweaker v5.4.

Fixed in 7+ Taskbar Tweaker v5.4.

Fixed in 7+ Taskbar Tweaker v5.4.

A duplicate of:

http://tweaker.userecho.com/topics/725-support-for-windows-10-fall-creators-update/

A duplicate of:

http://tweaker.userecho.com/topics/725-support-for-windows-10-fall-creators-update/

I can see no reason why hover will not show the thumbnails in all cases (active or not etc).

The thumbnails should be shown even when the program is not active. If it doesn't, perhaps it has something to do with your settings. Check your "Hovering" option in the tweaker, perhaps it's set to "Nothing"?

I'm not sure I understand the question. The "Open last window if inactive, otherwise open thumbnail preview" option doesn't affect hovering, you still should be able to hover to show the thumbnails.