Changing the scene text after an event in the Harlow theme turned out to be quite easy (once it was pointed out to me, thanks Greyelf).
To do this, you need to create a variable in the first passage (launch passage)
(set: $visited to 0)
The variable can be called anything as long as it has the “$” before it.
Then is the passage that you want to change add
(if: $visited is 0)[
The first visit text goes between the first set  between the $visited and (else) and the second set (changes to) in the second set.
The when you come to where you want the event that changes things use
(set: $visited to 1)
when will then trigger the change in passage text.
This just scrapes what can be done with variables, but it serves me