The pic you posted is not F-22P which PN operates, below is the pic of F-22P of PN:
View attachment 210792
Yes, PN must have at least 4 ships in class and capabilities of Type-54A.
Why PN want larger version of F-22P when they can have much better Type-54A customized as per their needs, also later is modern hull design then prior one because F-22Ps are based on older Type-53.
F-22P are an adaptation of the Type 053H3 frigates but include elements of theType 054 frigates as well. So its a hybrid, only downside was its SAMs which if they can correct in a newer version then it will be just as capable. Pakistani Navy is a defensive force, a larger frigate will have more endurance but same capabilities so doesnt need the larger ships to project power.
As for ordering more, maybe its more feasible since we already built the last ship lat F-22P in Karachi, since TOT is already done. All new ships could be build in Karachi shipyard.