Are they any possibilities that some words exits in US dictionaries but are not in UK dictionaries because they are not used or common there?
Therefore, there is a discrepancy in the lexicons of English varieties.
There are indeed some words that exist in some varieties of English and not in others. There are also words which have different meanings in different varieties.
However, there are a number of words which are so rare in all varieties that it is simply a matter of which words individual lexicographers admit. Your three words come into that last category, IMO.
None of the three can be found in the Corpus of Contemporary American English.