IMO what PLA really need is to make the 155MM part of battle order for the HBCT , with the proliferation of drones these days , the father away the artillery piece is , the safter it is .
I don't think the 122MM is going to be enough .
Having 122mm tube artillery as the standard brigade level tube artillery means you have greater mobility and greater ease of logistics for your organic brigade level artillery (including in terms of having a sufficient amount of ammunition to actually sustain fires, easier to replenish, easier to reload by the crew due to smaller ammo).
That is quite important for letting your combined arms brigades maneuver more quickly, whereas having 155mm organic could slow them down a bit more.
Having 155mm tube artillery at the group army level means that you have the preexisting command and fire control infrastructure that enables large scale coordinated fires at the group army level, while also still having the ability to delegate select battalions to maneuver combined arms brigades to augment their firepower.
What's important from the PLA's pov, is that the total number of 155mm guns that they have in service is actually quite large (and with PCL-181 is growing quite quick, and is likely to grow even more as PLZ05B enters service soon), so as far as total 155mm tubes go they're not actually deficient.
It's just that the 155mms are organized in artillery brigades under command of group armies to enable large scale coordinated fires, but still have the flexibility to be given to combined arms brigades on a task needed basis.
Yet on top of the large number of 155mm tubes, they also have 122mm tubes organic to brigades as an "added bonus".
