Glad to see that you went back. From their perspective, you were the rude foreigners who came into their country and jumped on all of them for no reason and also shaming them in front of other people who were there. Maybe not even the first group of foreigners who acted like that. Thankfully, you realised the mistake and even gave a gift. You did the right thing and I bet it felt good to them.

I saw a YouTube video about a grown up black guy living in Japan since his childhood. They asked him to mention a racist experience because of "How discriminating the Japanese people are!". He absolutely couldn't mention anything specific. No memories of such. He could only mention a memory vaguely when little kids in elementary school fooled around because his skin colour was different. So basically, kids being kids when they see something they don't see usually. As a grown up, nothing. Of course, this isn't the 100% truth and true for everyone there but this whole situation seems like an exaggeration. Saying "you are sexist, bigot, racist, etc." slurs for silly, baseless reasons... Mostly driven by strong emotions. What I hear is that they tend to be polite and tolerant. Japanese people don't seem to have this obsession of labeling others while people from Western countries more likely do it. Whatever the topic is, soon it is lead/forced to "oh they must be this or that". Even in everyday conversations about casual topics, movies, tv series, sports, gaming, some people come and act like zealots and start to attack and label others when that's not even the case. There is an article like this on some newspapers every day targeting someone or something. And after a while, it is boring, unbelievable and people get tired of it. Really, there is no limit these days after the "sexist air conditioning" drama.

Don't go hard on yourself though, mistakes were made but you did the right thing in the end and probably you will change other people's thinking too.