Yes, this was the conclusion of the mech (he told me that this kind of issue had already been experienced, including other models than Pantera), and fact is that after its deletion, there's no more issue... but from a strict logical point of view, it doesn't prove that this part was at fault ! I guess that something else was modified (don't know what) and solved the problem.
He simply put one single limiter on the left hard brake line, and another one on the right line, and balanced them on a rolling bench.
By single limiter, I mean a small device allowing to adjust/reduce the output pressure level by turning a button.
Matt