I kinda like your idea xD
Well, you can go upstairs literally anytime though. The only places I set switches to prevent the player from moving are the guild and the city gates, so if the player forgets what to do they don't just go running off the entire world trying to figure it out lol. But RPG Maker and it's events are kinda weird and changing priorities may make one impossible to interact, so at some point I may have messed up the upstairs event and given you a false impression. If so, oops, sorry!
I may just make Lianna's message clearer saying something like "time to walk upstairs" now and then so the player knows what to do from the start, and the receptionist not teleporting you to the room should help too. It also doesn't help this is an early access game so it's easy to forget basic stuff between updates ;-;
Anyway, thanks a lot for playing! It's weird to say the journey is pretty close to ending, but I hope to see you through to the end! <3