I used it in pre mode too. But here everything is banal. A specific analysis and service are needed for a specific breakdown. This requires services, knowledge, tools.
Why adjustment to crossover point is significant change? It can be anywhere. But resulting frequency response matters. I mean what the difference in crossover point if frequency response is seamless? I do not see any crossover joint.
But from measurement point it is really interesting to know why sound of R3 Meta differs from original R3? Where is it on graphics? I mean real difference nor difference error or assumption.
What specific device do you use? I can't see buffer bypass or turning on directly. Maybe I need to be more attentive. Blue colored PCB.
I see Nord NC500 buffer.