Not sure if makefile is the best place so everyone put the target names he likes... at the end, this could end in N x 2 different "alias" target (N equal to the number of developers).

I'd suggest to alternatives:

1. Keeping the per-developer custom targets in the local copy of makefile, don't commit it to the repository
2. If we don't find unit_test or functional_test names appropriate and we prefer utest and htest (no problem with that from my point of view) then change the names, but doing it consequently, including all the places were they are used (e.g. README.md, jenkins, etc.). In addition, we should take into account the impact in other people using our code.