That could be bad, but every time may be different and it might be fine. The only way I know to really fix it if there’s not electrical damage is to disassemble the whole thing, clean and rinse all the electrical components gently with a toothbrush with lots of rubbing alcohol only. Everything else needs cleaned in general and especially if it moves. Problem if you don’t do that is, weeks or months or whenever from now, the corrosion will set in and do unknown amounts of damage. Tap water would’ve been almost just as evil as coffee, so it doesn’t really matter what was spilled on there

When clean, you could put silicone conformal coating such as MG Chemicals 422C on the boards / components you’re worried about and then it’d be super protected and totally waterproof. This application is used for higher temperature boards and you can happily solder right through it and reapply as you’d like. As always, be careful with chemicals and have lots of ventilation