What do you mean with “united states” specified, because those two words specify very little? Did you select the USA in the issuer field or did just put ‘united states’ in the general search field and expect only USA hits? If the former gets hits other then USA it's a bug, if it's the later it's quite strange to expect that result, it's normal alphabetical sorting behaviour. You get hits from any page that contain your search terms then they are given out sorted by issuer alphabetically. And guess what … U is quite near the end of the alphabet.
If your search queries are too long you usually add more information or filters to reduce the hits to stuff that actually interests you. Like if it's from a specific country and you don't want to endlessly scroll, select the right issuer, if you search for a silver or a copper alloy coin, select the material ‘silver’ or ‘non-precious’ so you get less false positives.
The “simple” search checks everywhere so the hits are generous.
For the 1st query the Peso contains all the search terms
The 2nd one I also find no obvious reason. I thought for Brazil it could have been the issuer United States of Brazil but that came after.
The Japanese Hakodate-tsūhō also doesn't contain the search terms, the nearest is the word USA in the comments which might have a equal value to United States like in the issuer somewhere but that feels like a stretch.
The 3rd query is like the first they have Peru either as a comment or mint etc.
The 4th, yes all of the UK colonies were put together so you will get extremely many hits with a generic search.
The 2nd search is to most illogical as I can see nothing abvious why these pages came up.
But also to be honest, most if not all your issues would be solved if you would simply select the issuer and not keep it on ‘all’.
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