I've had a similar situation to you anon, i went to Japan and Korea for 1 month with 2 highschool friends that i wasn't super close with anymore, but we caught up occasionally. We had a lot of conflict over what and where to do things, even though we had pretty much agreed on the schedule and they weren't making any effort to organise or plan things.
Honestly, if you're the one calling the shots and they don't have any plans or apparently "go with the flow" and then get upset about stuff you have to be really strict on saying "fuck you" to them and let people do their own things. After a few days in the country, you should have learned the subways, have subway apps, etc. and its really not worth lugging around a complaining friend.
Even better, try to weed out what people do and don't want to do beforehand, so you can either plan separate activities or just avoid the emotional burden of having to deal with it on the spot. Sounds like your super introverted friend is going to be complaining a lot about being tired, having her feet hurt, doesn't want to go to this place because it'll be too late, doesn't want to eat here, etc. LEAVE HER AT STARBUCKS. Tell her to eat on her own. Tell her to go home, or leave her at home if she's being stroppy. I had a really disappointing time (mainly in Japan) because one of my friends straight up doesn't like japanese food.... and its my favourite cuisine. I also missed out on many things because my friends were too tired or not interested, but didn't want to split the group up (why, i'll never know).