How to clean a calcified bathtub outlet that I can't dismantle?
If you can't remove them, you can use lemon juice or vinegar. The challenge will be to soak those filters without the liquid going everywhere.

If the seal around the faucet is good, I'd probably get a small container and some putty and cut the bottom of the container so I could place it over the faucet.

Use the putty to temporarily seal around the container and then fill it with lemon juice, vinegar or a commercial decalcification solution so the filters are covered.

Then just leave it for a few hours - this should work very effectively.