Some suggestion for your mod (Which is great otherwise, thanks!):
Allo to control the train depot from the circuit network. Thus, you can request creation of train through this
Another idea is to add control per construction site.
In my case, I have 2 construction sites, one for cargo, one for fluid. So, depending on my needs, I can send a signal to create a cargo wagon or a fluid one... But this second idea is not so urgent, as I can always have 2 depots, if necessary.

Thanks
Hermios

At least, please allow connection from logistic network to your depot train station (I need it to connect my system, so I can control automatically the train which arrived in depot).
Thanks
Hermios