Western brands like Hilton tend to have bigger rooms (and bigger beds). Also there are "family style" hotel brands like Mimaru that are lower price but sleep more people. They even have a little kitchenette, large table, etc in them that make them more apartment style.
If you want to do a ryokan experience (which I recommend!) usually they have rooms that fit four people.
As far as the language barrier, the various translation apps are a lifesaver! Many restaurants we went to, the servers would speak into the app to help us. Google maps works really well, even tells you the exit number to use for every train station (each door is numbered, with clear signage, so once you get the hang of it you can really save yourself a lot of walking).
