After 301 redirection non-English keyword points to English language pages

[OptiMal]

Hi,

So the situation looks like this

• website domain1.co.uk in not regional - it's in only for UK but had multiple languages
• polish language pages on domain1.co.uk website were redirected (301 redirect) to domain2.com but with /pl "bit" so: domain1.co.uk/page1 > domain2.com/pl/page1 and domain1.co.uk/page2 > domain2.com/pl/page2
• when user in UK look for Polish keywords, for some the keywords, the result is correct (it shows domain2.com/pl/page2) and for some Polish keywords user in UK got served domain2.com/page2. Please notice that in both cases is the same location and different polish keywords.
• pages on both sites was mostly "mirrored" which means article in Polish had English equivalent, so even when Polish user gets to English page, it's still relevant, thus increasing bounce rate as user don't necessary have to understand it.

Where would be the problem? Incorrect links for Polish keywords leading do English page or something wrong with redirection?

Thank you.