Done:
https://translations.documentfoundation.org/translate/libo_ui-master/officecfgregistrydataorgopenofficeofficeui/en_GB/?checksum=baaeec7b02a1e43d&q=note%3A6NozA&sort_by=-priority%2Cposition

I also tried to fix all the occurences of it.

I notice that some other words should be checked, eg:
"customise" instead of "customize"
"organise" instead of "organize".

Stuart: any thoughts here?

Meanwhile, let's put this one to FIXED.(of course, we'll have to wait for the synchronization between Weblate and translation repository + next LO release which will include the fix)

I'd left 'Dialog' alone in BASIC and Macros as it's more of a programming element here.

Indeed, many words tend to have -ise(d) etc endings in common usage in the UK.

Argh, do you mean kind of word of "programming language" and not "English language"? If so I suppose I should revert all the changes I did here and put this bugtracker as NOTABUG

It's one area I avoided changing for that very reason! You don't want to stop existing Macros working.

ok I tried to revert all the things I had changed (I let "organise").

I noticed this with "Dialogue":
https://translations.documentfoundation.org/translate/libo_help-master/textshared01/en_GB/?checksum=85a0b21121cb7c53&q=note%3AM7NqY&sort_by=-priority%2Cposition

it's not clear for me why it's ok there but since it was ok for you, I'll let as it is.

I put back this one to NEW since I don't know what should be the status then.

I am familiar with the use of “Dialog” in programming, but as this is the LO-UI why would using “Dialogue” affect BASIC/Macros?

The Dialogs that it's offering to be organised on that menu entry are those provided for programming purposes, so I'd stick with Dialog here.