But you started out already knowing the marriage was at St Andrew's:
If a marriage certificate 1914 says:
Marriage solemnized at the Parish Church in the Parish of S Andrews in the County of Leeds - how does one find out which Church that is/was?
We've explained to you:
(a) there were a number of churches in the Leeds area called St Andrew's, but the descriptions and reference numbers at Yorkshire BMD and in the WYAS catalogue point to it being the one in Cavendish Street
(b) St Andrew's parish was created out of the parish of St George's (and was later reunited with it), hence it sharing the same reference number in the WYAS catalogue, but in 1914 they were completely separate parishes
(c) normally there's only one parish church in a parish
(d) the bride lived more or less next door to St Andrew's in Cavendish Street
(e) the register/certificate clearly states that the marriage took place in St Andrew's
So I don't understand where you're coming from now. At the start you wanted to know which St Andrew's church it was, and presumably where it was, and we've told you and explained how we reached our conclusions.
Unless there's some reason you think the marriage took place somewhere else, that you haven't told us about, surely that's the end of it?