You make it sound like the 022 has a VLS when in reality it just has standard slant launchers (beefed up metal frame) enclosed in a stealth housing.
Unless you are trying to integrate something grossly too large (and there are plenty of off the shelf options that can easily fit within the existing housing footprint to require zero structural changes), integration is so easy it’s something that can be done by a few qualified welders in the field. The only expense worth mentioning is a few test firings and maybe some electronics upgrades. Maybe expensive for you or me, but peanuts for military budgets.
As for the utility of 022 launches LACMs, well sure, the PLA has options aplenty on the west coast of Taiwan, but having 022s pop off LACMs on the east side of Taiwan options up all sorts of options you cannot really easily hit with mainland based fighters or land based launchers. Not without a significant detour that presents significant costs in terms of fuel, security and risks.
Once PLAN carriers and other principle surface combatants have secured sea and air control around Taiwan, the only serious risks are USN carriers and subs. USN Carries would be a top priority for the PLAN’s own carriers, and would be at significant jeopardy itself to get within fighter range of Taiwan. Even if that was achieved, do you think USN F35 pilots will want to take pot shots at 022s? Same deal with subs. You think any USN SSNs that do manage to get within weapons range would waste their shot on 022s?
That is the strength and beauty of using 022s for large munitions expenditure strike missions. They can move without close escorts to and from launch positions and face almost no threat because anything that can get close enough to threaten them will not want to waste the opportunity on something so puny.
Sure you can use 052C/Ds for strike missions, but every VLS you use for LACMs on 052C/Ds is one less for SAMs and AShBMs. And what happens after your CSG escorts have run out of LACMs? Send a replacement escort fleet to tag them out so they can return to port to restock missiles? At what point do you do the swap? Where would your returning ships need to go to safely rearm?
Why create those difficult choices and added complexity when you can just keep your 052C/Ds and 055s on station with full missile loads while 022s can zoom back and forth to do the missile spamming instead?
That’s actually adding significant value to the mission instead of just sending them out with load outs that are almost certainly not going to be needed or used, which is basically just sending them out for the sake of sending them out since you have them.
So, to clarify, your envisioned use case for the Type 22s is to replace their AShMs with a LACM that can be fit in the same dimensions and weight footprint as YJ-83s, and use them as LACM platforms to sail to the east of Taiwan specifically to attack the east side of the island?
But there are multiple questions that emerge immediately:
1) which LACM can they even install on the 22s? The Type 22 are small ships and their topside structures are designed to accommodate the Yj-83 family weapon in terms of length especially as a major limiting factor but also in terms of topside weight. Do you suggest they adopt an existing LACM or develop a whole new one that fits the YJ-83 footprint?
2) your CONOPs requires the Type 22s to sail to the east of Taiwan -- sending a FAC into open waters all in a ship with poor sea keeping.
3) if the goal is to strike targets on the east coast of Taiwan, why does the PLA even need naval platforms as launch platforms to physically go to the east of Taiwan in the first place? SRBMs will be able to strike those targets, and they have plentiful fighter and bomber aircraft with ALCMs and SOMs where waypoints in a flight mission are very old technology. To strike the east of Taiwan they don't actually need any air or naval platforms to be easy of Taiwan to employ their weapons -- they can simply remain in Chinese airspace
All of which is to say -- the Type 22s are a bit of a unique novelty weapon for a single purpose with limited physical space for growth or modification.
If they have to be used in a conflict like a Taiwan contingency, they are not able to contribute much which other platforms cannot do much better, and any role they should take on should suffer from as little effort, time and money as possible to make happen.
The best role for Type 22s is just give them modern YJ-83 variants with dual mode guidance which does not require them to spend any time, effort or additional money to modify the ship or ensure ship stability. They can contribute to anti ship fires during the early phase of the conflict as glorified/more mobile AShM TELs operating in China's littorals, and in the later phase of the conflict if they have to be used, they can fire dual mode YJ-83s against land targets if needed in the same manner.
Alternatively, they can just be stripped of their AShMs and operate as simple high speed patrol craft in Chinese waters.
These are not platforms worth using any effort to give them a mission outside of their immediate scope for.
Frankly, if the Type 22s had VLS that would be simpler because at least that way there might be other VLS launched missiles they could employ.
Bur given it has slant launchers on such a small ship, if they want to replace that with another slant launch missile that doesn't have the same dimensions and weight distribution, then you are in for a whole lot of effort to make it work.