To my ears these are good matches:
Meelec balanced - open, transparent, less mid bassy
Sensorcom biflanges - deep bass and quite a lot of mid bass, quite transparent, good treble, not as open.
MH1C hybrids - strong bass response, good balance in mids, a bit aggressive less open and more directed but still good placement.
Comply TS500 - Softer sound, comply-ish bass texture, bass lines really stand out. Upper mids are softer and more relaxed. Treble is a bit more subdued.
Hi MoonYeol, do any of these tips fit on the FA-4s without having to really force them on?