So after some thinking I came to the decision, that efi variables are the better way to go for me.

I just need 9 values and I map them from 0 to 9. I created a efi variable with 9 words separated by spaces and just implemented a function which saves the words to an array.

For a greater application I still would recommend using a config file for the ease of use, but writing a parser for just some values would be overkill.

You can look at my test application here:
https://gist.github.com/KastenKlicker/a1947bec5254d16646dd88484ce8b59e