I like to think of the Type 054A as an ASW platform as well. If its VLS cells can hold anti-submarine rockets, then it could potentially be a very capable unit and a crucial component of any CBG when coupled with aerial assets.
Even without VL Asroc, having a TAS, bow sonar, and a helicopter (and soon VDS), already makes 054A a good ASW option for blue water, and maybe as a control ship for 056s and other assorted airborne ASW assets in green water.
What the PLAN needs is more proliferate numbers of capable medium sized ASW helicopters (basically an ASW Z-20) among all its current ASW capable ships. On bigger ships, like maybe 055 or other future DDGs and FFGs, they should look into larger helicopters like the merlin sized Z-18FQ as a standard complement.
Closer to home, they need to hurry up their Y-8GX6 development and don't stop producing them until they have a few regiments to form a core to build around, and also hurry up with their SOSUS network. Thankfully, it looks like they will soon have a large number of 056As with TAS, VDS, and bow sonar to cover green water, but they need the longer reach of a fixed wing ASW bird, and other ships with organic helicopters, to deliver the prosecution.
Not an expert here, but could the Type 056 theoretically work in tandem with the likes of the 039 submarine, in which one unit would carry out scout duty while the other one packs the punch?
Thing is, it's probably more efficient using your own submarine force to pick off enemy surface ships or submarines instead of having to pair up with surface ships as a dedicated ASW attacker.
That doesn't preclude submarines maybe receiving targets of opportunity from surface ships, but as a dedicated appendage of a surface ASW ship, they will simply be too slow to be as effective as a helicopter.