I suppose at least 'worker' should imply someone being paid for their services.

I think the first 3 you list don't really work very well in this context (as you say). However, 'coordinator/worker' describes rather well the relationship of the objects here.
A few alternatives to replace 'master' along the same lines could be 'manager', 'director', or 'controller'.
But I'm struggling to come up with other good alternatives to 'worker', which could maybe still be taken to be a bit pejorative? Maybe 'runner'? Any other ideas?

OK great, yes confirm the changes in rLAURA696d6d44a70e fix these concerns.

The CI build in the gitlab mirror of EvtGen is now working.
I've also committed the necessary changes to switch to using jsoncpp from LCG.
The build and test run successfully and you can see the details of the CI pipeline here:
https://gitlab.cern.ch/evtgen/evtgen/-/pipelines/1883808
I'm running everything in LCG_98 now because that includes the new versions of Photos and Tauola that include HepMC3 (btw it also includes EvtGen 2.0.0). There are now 4 builds:

• gcc9-opt
• gcc9-dbg
• gcc10-opt
• clang10-opt

and a test that uses the gcc9-dbg build. At present the test just runs your testDecayModel on one of the example json files you provided.
One thing I've noted is that the lack of a reference file does not result in the test exiting with a failure code, so that's something we need to look at.
The next step will be to analyse the contents of the push to see what files have changed and based on that work out what tests need to be run, etc.

In T108#1684, @jback wrote:

The idea is to run a test doing:

./testDecayModel jsonFiles/example.json

where the json file defines the decay model, particles, parameters and histograms, as well as a reference file for comparison. We could then test the chi-squared values and print out a warning message if there is a large difference.
This then allows us to use this single test program to compare many decay models, which could then replace evtgenlhc_test1 and do_tests, without writing additional C++ code (unless we want to add other histogram distribution types).

The clang-format part of this is essentially done.
The naming conventions etc. are still to be unified and written down.
Similarly, the rest of the CONTRIBUTING document needs to be written.