Visit Aqua's room at night to get drunk first; I'll probably add that as an additional hint to Lolisa's event
This unlock condition is a bit dodgy. I imagine the average player may have gotten drunk with Aqua at her room once during the story, twice to clear repeatable for extra dialogue and THEN unlocked the cafe, never figuring out (because the unlock condition is hidden and players are overwhelmed with content at this point) that you are suppose to visit Aqua again (which you didn't need to do because you already have enough affection).
As far as I can tell, there is no meaningful hint. It's true that Lolisa showed up the night he drank and had visited the Succubi cafe in the anime. But due to the setup of the sandbox, people can very easily miss it.
Perhaps add another subtle hint that triggers if you haven't unlocked her already? Momo could perhaps tell the player something(through the highlightable text?) if we pay her for a service?
This was the only thing I personally had to look up. Entire time (until the very end of 0.2.1 ) wondering where she is.
Tldr; consider adding a hint that shows up if you haven't met Lolisa after some time has passed but have access to the cafe and can Hang out with Aqua. Perhaps through Momo.