Ask Aeroflot directly if they will transfer bags. Also, you need to make sure that Jeju Air can give you a boarding pass at the gate OR if they have a transfer desk presence (Not sure about that one myself, but my guess is no as it's an LCC). That is the only answer.

If you 1) cannot transfer bags or 2) cannot get a boarding pass from Jeju Air online or at transfer desk etc. - this ticket will not work. Because doing both or either of those things requires you to enter Korea to get bags and go back to check in area....and no one can do that now with quarantine restrictions.