Back again:
Have now solved the issue with the welcome screen showing pictures with different languages. According to posts on Reddit this is to do with "Windows Spotlight" - though there maybe a more underlying issue.
one solution was to look at the language setting for spotlight - however this seemed ok. T
he other was to simply turn off spotlight and just use a picture (go to settings - lock screen settings and change windows spotlight to picture and select a picture)
I did the latter for now.
so this plus resetting the region seems to have improved things.
But need to keep a check to see if this language problem occurs elsewhere
(note I had inadvertently asked mS copilot about the issue yesterday and the prompt box for a reply to this was in Chinese - resetting the region to English and my country (even though showed it was set correctly) has also solved this as well as the Chinese on the logon screen - just did a check! )