> i dont think im experienced enough to place them on the nozzles

Its pretty trivial, filters have the adhesive applied in a cirlce shape on the edges, you just stick them on the inside ledge of the nozzle holding them on a needle tip or with tweezers. You just need to make sure to measure the nozzle size so you get the right size filters, nothing more to it. To remove just use a needle and go around the edges and try to stick it underneath, then just peel.

And would probably benefit you, since you say you dont like treble and they do affect mostly upper mids/treble.

Heres an example of the effect they have, it 200 on top going down to 500 filter. 200 is pretty close to just steel mesh(screen door like filter), and 100 would probably be like no filter at all, though havent measured that one. https://imgur.com/FPDYflL

And now you have some spare nozzles to experiment with :).

For more bass plug the vent near the nozzle, you can use micropore tape(found in pharmacies) or even better try different density filters there to control the ammount of bass, and to reduce bass plug the vent farther from the nozzle.

Edit: This is not a kato measurement in the example, so dont know what is the starting point/effect the kato stock nozzles/filters have on the sound signature.

Never, never and I mean NEVER!! clean IEMs with alcohol, alcohol is a solvent and could damage the paint and/or the glue, I know you want to have clean your IEMs but alcohol is too strong better use some baby tissues or a degreaser for oily skin, at the end of the day that's the only thing you should clean your IEMs from.

You could try to re apply it to the nozzle but if you already ordered a new pair I don't know how much do you want to have 2 pairs of each filter.