Hey, related to the comments, you can input text in UE Wayland by holding Alt.
It’s not super convenient, but in Plasma at least you can also go into preferences, search for X11, and there should be a window titled something like “Compatibility of inherited X11 apps” (not sure if it’ll be called like that, I have it in Spanish).
There is a field called something like “Allow inherited X11 apps to read key presses of all apps”, which you can set to “Always”, and then Unreal will automatically read the text input. You’ll get a security warning tho, so I guess is also not the best option. It’d be great if we could configure it per-app, or even better if Unreal was updated to Wayland, but in the meantime these are the workarounds.