I wanted to point out that, in your mod description where you say this

Ghosts show their recipe, but not their planned modules — ghost inventories cannot be read.

You can actually read items that are planned to be inserted via LuaEntity::insert_plan. Note that on real entities (non-ghosts), you must first obtain item_request_proxy if it exists, and it is the proxy that contains the insert_plan.

I know there's a lot of attention to detail that goes into quirky interface mods like this, so I wish you good luck!

Thanks for the tip. It might not turn out perfect, but I'll try to integrate as much of the original as possible.