The fins will grow back in no time. It will grow fast in warmer water above 84F.
About the tankmates, it will may not bother the african lungfish but those bottom dweller such as the bichirs will soon be a goner. Not just kill them lightly but brutally. I learned that the hard way myself when I tried to prove to everyone that they can be keep with tankmates as it took him 6 months when the mass killing started. All my bichirs and gars head were crushed. It only took it one night and all 7 bichirs and 2 gars were dead. Some bichirs survived with some nasty bite marks.
All African lungfish are unpredictable and have a very powerful bite. Some have successfully keep them in a comm tank, but 98% of the time time, they become murderers.
You maybe able to get away with a South American Lungfish or an Australian Lungfish.
keeping this fish with arows, datnoids, polys, after all the warnings and information about African lungfishes being poor tankmates and needing their own tank is irresponsible and stubborn.
as many have said already, the fish WILL eventually attack, and it is your responsibility as a fishkeeper to make sure the fishes are generally kept in an appropriate manner and in healthy conditions. ignorance is one thing, but this is general irresponsible husbandry. i would strongly advise separating the fishes as soon as possible--
--solomon