The new resource editor is indeed a proverbial pain in the backside. Even after a few more updates (currently on 7.11.5) its still buggy as f***.

Currently for me its even causing my entire Visual Studio to crash, loosing code in the proces.

For now my workaround is to open them trough right click -> open with and select Managed Resource Editor (Legacy). Just select this option and press the Default button to revert back to the classic editor as a default till Microsoft can wrap its head around and fix it.

Perhaps Microsoft can also learn to release features like this after a more extensive testing phase as should be done with all software development?