I should be able to post in much more detail later, but I think this comes down to the difference between a ‘plural result’ and a ‘tuple result’.
We separate tuple items with a comma, while we separate plurals with a semicolon. We can concatenate plural results, but when we concatenate tuple items it still results in two separate tuple items unless we’ve explicitly converted them into a plural with the use of a semicolon.
Either of these syntaxes should be a start -
(Tuple string item 3 of it & " " & tuple string item 4 of it)
Concatenation " " of (tuple string item 3 of it ; tuple string item 4 of it)
(Note the semicolon rather than comma in that concatenation)
Otherwise it may be simpler to deal with the last semicolon first -
Substrings separated by ";" of (Preceding text of it & " " & following text of it) of last ";" of it
This joins the last two fields first, removing the semicolon between date & time, before then splitting the rest of the string on semicolons. So when the whole string is split, the last semicolong having already been removed, the date & time are together in one field.
(Edit - typing on my phone now, I’m unable to test at the moment, will verify the syntaxes later)