Sorry to hear you are having trouble typing polish letters in XD. Would you mind sharing the Operating system you are working on and the screenshot of your XD info page so that we can try to replicate the same at our end?
We will try our best to help.
Windows 10 Pro
Adobe XD 188.8.131.52
Thank you for reaching out and sharing the above asked information. The team has logged a bug for the issue and they are working on it. I will get back to you as soon as I hear back from the team or if they need more info for investigation.
We are sorry for the inconvenience.