As far as leulupi and brichardi as tankmates with Front, if you have a lot of rock work, it may work. Leulupi and brichardi are rock dwellers and don't stay out in the open much so the Front won't be able to get them. And if you raise them together, the Front won't view them as prey.
You may have problem with open water tankmates with Front. The aggressiveness of Front is underrated because as once they reach sexual maturity, Front can be a killer in a small tank. I have one male Frontosa that successively killed half a dozen 6 to 8 inch haps in a 75 gal tank. Front is so big and powerful that it doesn't take much of its effort to kill any tankmate he doesn't like.
You may have problem with open water tankmates with Front. The aggressiveness of Front is underrated because as once they reach sexual maturity, Front can be a killer in a small tank. I have one male Frontosa that successively killed half a dozen 6 to 8 inch haps in a 75 gal tank. Front is so big and powerful that it doesn't take much of its effort to kill any tankmate he doesn't like.