This page will contain several pieces of advice about using OpenFK.
OpenFK has been made to closely mimic the original UBFunkeys.exe, reaching near feature parity since v1.5. However, due to the way OpenFK was made, it can still have issues that only occur with OpenFK. These primarily occur in areas that have not been fully implemented and tested. These include the Paradox Green minigames and network connectivity. If you can find replicable errors with OpenFK, make sure to place an issue on GitHub.
OpenFK v1.3+ supports decoding of the game's RDFv2 files. However the decoding process is not perfect, as there are issues with special characters which return garbled text instead. This can make the in-game text hard to read in localized versions of the game. OpenFK also does not currently implement decoding of RDFv1 files. This means that you will have to manually provide XMLs if you are playing older versions of U.B. Funkeys.
OpenFK handles the 'netcommands' function that is required for the game to properly communicate to external servers. However, there are currently no active servers for U.B. Funkeys at the moment. There are projects such as UBFunkeysServer and A1Emu that aim to reimplement the servers, but they are out of the scope for the OpenFK project.