- It sounds like a Japanese woman saying it

Nothing Japanese in it. Japanese has no uvulars, no glottal stop, no rounded front vowels...

- I know Japanese have difficulty with "R"

Actually, they don't. They have a problem with "l" (which does not exist in Japanese). Japanese "r" is just an alveolar tap [ɾ], not a trill, which means that to our ears it sounds superficially similar to d or l (in fact, phonetically it is practically identical to "t" in certain positions in American English). Spanish "r" is similar (unlike "rr", which is a full-blown trill). In loanwords from European languages Japanese replaces "l" with its native "r".

- "rest" tends to sound like "west"

Not at all. Actually, this is a characteristic of English (not Scottish!) "r", which is very peculiar sound.