Not here in English. Normally only ever see redline if someone doesn't spell it correctly, if I then fix the spelling it removes the redline as it should.

If it happens a lot in Finnish then can only suggest to send feedback to Microsoft. That is WHY it's in beta to get feedback. But if you remain silent and thousands of others remain silent then how can you expect Microsoft to even think about fixing it.

No complaints, then it must be okay. You can't just complain about it here or other boards and expect it to ever get fixed. You have to provide Microsoft with feedback on the issue.