What is not known. Nothing here is disguised as an answer.
The table at 0xAD60 dispatches forty enemy behaviours, and each one is a routine of its own. They are all traced, all commented and all reachable - but they are named comportamiento_0 to comportamiento_39, which is the only thing that can be stated without playing each of them. Reading the code tells you how one moves; it does not tell you which enemy on screen it is. Tying each number to the thing you see would need a run per behaviour with a breakpoint on it.
Five of the forty do double duty as the boss's shots, which the table at 0xAE9E names again: indices 6, 7, 8, 9 and 10.
The 57 tunes at 0x511A are decoded -the language the interpreter at 0x4F06 walks is documented- but none of them has been listened to and matched to a moment of the game. Which is the title tune, which the stage tune and which the one that plays when a bell is collected is not written down anywhere here.
monta_la_fase_para_el_game_master (0x4103) fills four variables out of four tables: 0x4153, 0x6132, 0x61D5 and 0x6210. The first one is the height at which the boss appears, and the other three are landmarks the scenery compares itself against as it scrolls: prepara_el_marcador (0x610E) fires the boss when the map reaches (0xEBB6), mira_si_toca_nube (0x619D) fires a cloud at (0xEBB0) and mira_si_toca_musica (0x61E9) changes the tune at (0xEBB3). What is not clear is why the boss table has four entries for five stages, when the other three have five.
la_tanda_del_final (0xBD2B) forces class 0x21 and sends them out one at a time, sixteen rounds, and recarga_la_espera (0xAEFC) gives that same class a special case: it does not reload its shot timer. It looks like the closing wave of a stage, but that has not been watched happening.
Nemesis (RC-742) hunts for the six bytes of this cartridge's mark through the slots. Whether Twin Bee looks for anybody in return has been checked and the answer is no: there is no RDSLT, no CALSLT and no slot walk anywhere in its code beyond the ENASLT of INIT. Whether any other Konami cartridge looks for Twin Bee is a question for those cartridges, not for this one.
0x44EC writes into 0xF0FF a value taken from the service bits of the second joystick read, and three places read it back: 0x5D73 gives you power at the start, 0x5D7A gives you bells already loaded and 0xA3F7 doubles the weapon uses. What key combination produces each value has not been worked out - the byte comes out of (0xE063), the whole row-5 keyboard read, and matching that to actual keys would need a run with a breakpoint and a hand on the keyboard.