People from russia (and perhaps Ukraine too) have more challenges with English pron than Native speakers of Polish.
Quite true. I''ve followed some Russians online who write English at native level but when I found spoken interviews... yikes! I can barely understand what they're saying..
A person's first language shapes their speech apparatus in ways that make some other languages essentially impossible to pronounce really well.
That said, I've had several Russian speaking students who do manage reasonably well.
(Polish speakers are not disadvantaged in English but are horribly disadvantaged in languages in which vowel length is important (Japanese and some other Asian languages especially) they seem really uncapable of producing short and long vowel sounds).