OK. Thanks for the feedback. The ‘fix’ I provided was a start, but it missed the real issue, and also introduced a new one, so please delete that and revert to the original file (I can supply a copy of that if you need it).
The ‘real’ issue was surprisingly in the en_GB.mo translation file.
Please try the attached version.
Remember to go to Admin > Site Administration > Clean up data folder and delete the “cache’ folder completely. Then return to and refresh the Reports pages. I’ve tested most of them and they are working OK for me, but it is still possible I missed one.