Is it the case that auto splitter only works on patch 1.27 or am I missing something - I'm abit of a Newby

yes, it only works for patch 1.27 unless you don't want to create an auto splitter that works for the latest patch.

Okay thankyou, is this because the registered speedruns need to be 1.27?

And is it normal to use 1.27 just for the auto splitter feature?

second question: yes

first question: uuuuuuhhhhhh no, you can run the latest patch, but 1.27 is more convinent because of the auto splitter.

1.27 has more advantages than just the autosplitter btw. So the answer to your 2nd question is only a relative yes, there is more to it. Viper made a good video about it:

thankyou ive been struggling to find any videos on it, will take a look at this now.