Here's an idea for a Janitor strategy.
N1: Clean the Mafioso. If the mafioso doesn't die then this strat is over.
D2: Claim role as Medium, ask for LO and say you will get the dead players role and will the next night.
N2: If there is a real Medium the dead Mafioso claims Spy and posts an agreed will (true Maf Visits but agreed bug target). Since Medium's can't talk to each other at night the dead Maf can "confirm" the Janitor to the Medium by asking for their names.
D3: Janitor tells town the Dead Maf is claiming spy and post the agreed will. This could be confirmed by the other medium if there is one present.
If all went well the Janitor is now a "confirmed" Medium and unlikely to be lynched.
N3: Mafia must kill the Medium (if present) or the Janitor will be exposed very quickly.
D4: Dead Mafioso must convince the dead Medium (if present) to seance a mafia member so the Janitor isn't exposed.
Maf must quickly find and kill the NK role
Pros to this strat:
The Janitor is now a "confirmed" TS Role - throwing suspicion onto other TS claims
The Mafioso is a "confirmed" TI Role - throwing suspicion onto other TI roles and forcing them to keep quiet.
Counters to this strat:
A Sheriff would out the Janitor so fast since the Jan will show as suspect.
A Retributionist can bring back a dead player with knowledge of the Janitor's real role
If the Janitor is promoted to Mafioso an Invest will know they are not Medium