For the order you introduce transitive/intransitive verbs, wouldn’t it make things easier to remember to always introduce the easier to remember verb in the pair first?
My main argument is that it is usually much easier to correctly answer a verb review if you can also remember the other verb in the pair while you are doing the review. This is because often, at least one verb in the pair follows a simple rule like ending in -aru and then you can figure out the harder one by process of elimination. However, as the below examples illustrate, it seems less likely we’ll be able to do this kind of reasoning if you put the harder verb first.
広がる then 広げる (seems more effective to me):
Initial reviews for 広がる are still easy because it ends in -aru. Reviews for 広げる will be easy too since we will have already learned 広がる and can figure out 広げる by process of elimination.
広げる then 広がる (what you are planning to do):
Initial reviews for 広がる are easy because it ends in -aru. However, initial reviews for 広げる will be hard because you will not yet have learned 広がる.
Edit: Of course, ultimately, you want to everything without needing to do process of elimination. But just as with using a mnemonic, one will eventually begin to remember the answer directly without needing extra help as one does more and more reviews of the item.