Heya dude! Sorry for the late reply, and thanks for the kind words!
The hint system is designed to be a little out of the way - the intention isn't for the player to be 'spoon-fed' information - but the option to view it is there if one desires. But I do understand the pain of being on mobile, and the mobile version is something I'm hoping to revamp - I'll have a look into some optimisations for lower-end devices when it comes to menus.
For the issue of not being able to invite Ami over - it's most likely because you're running Ver 1.5.0, instead of 1.5.1. Ver 1.5.1 fixed the issue with this event, as it is permanently bugged in 1.5.0 - so I'd recommend updating to see if that solves the issue. Completing that event from Ami (Buckle) will let you continue with the main story :))
As always, new update is being worked on as we speak, thanks again dude! :))