Hi ganymoe
Officially, which means from Epics site, KDevelop is supported. In the community version https://github.com/3dluvr/UnrealEngine.git we have a QTCreator plugin so that you can use QTCreator.
Make sure, in the case of KDevelop, you have the following lines in your Engine/Config/Linux/LinuxEngine.ini file:
[/Script/SourceCodeAccess.SourceCodeAccessSettings]
PreferredAccessor=KDevelopSourceCodeAccessor
and restart the Project Browser again. Hopefully you will be able to create C++ projects. Btw, if you create C++ projects you will usual have a regular Makefile and CMakeFile in your projects folder. You can use the Makefile to compile your stuff and use whichever editor you want. With the CMakeFile you can create project files for other build systems. But that is not so well tested.