Hey Menelaos.
Because you are adopting 5arge's rules, I was wondering if you could add some further detail to the rules listed in the OP.
I spoke with 5arge personally so if you need any confirmation, feel free to speak to him.
So...
Artillery is allowed 10 artillery men. There can be 2 trains and 8 rankers or 2 trains 2 rankers and 6 officers. Any combination is acceptable including all the artillery units, line infantry, skirms, and engineers/sappers.
There is no limit on how far away the artillery pieces can be from one another.
Hopefully stating these rules explicitly will help clear up some of the problems related to the rules.
Thanks