So there's an oddity with kenshi where anything that is more than one step away will not appear on research lists. UWE is unfortunately rife with this.

I've created a submod that addresses this in all cases, and in a few very specific instances removes prereqs that do not make sense or are not material to the item.

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3621235907

Pending feedback from the mod author, this is due to change for balance but the research list fixes will not.