@heckflosse, Currently, the plugin is based totally on what DT used to do. So, It spawns a job with the executable and requires the executable to be on the PATH or one needs to define an environment variable called RAWTHERAPEE_EXECUTABLE etc.
So, if we go this way, then the current plugin could be fixed by calling the commandline version of RT (rawtherapee-cli) with -v and then that text can be captured from stdout.
Your fix requires the existence of a text file which if always guaranteed can work as well. I can try to work from these 2 point of views. What do you think?