I can only now do them pretty consistently on the stock d-pad to be honest. When i first got the ps5 it took me about a good 5-6 months to just begin to get used to it unfortunately. I do see what you mean about it being stiff, especially compared to the dualshock 4. The best way i think to get used to the new controllers/adjustments is to alternate between them. I predominantly use the ps5 controller now, but before i would switch between the ps4 for serious matches or ranked, and then use the ps5 for casual/ whatever i was comfortable in. What i can say is it is definitely something to get used to and it is awkward at first.