The answer to this is... complicated.
I've just run some tests and when you create a new bolted connection it edits the index.xml file here:
C:\Users\%username%\AppData\Roaming\Autodesk\Inventor 2019\DesignAccelerator\Templates\CABoltCon\index.xml
The templates themselves are also placed in this folder but are given a GUID-type filename:
C:\Users\%username%\AppData\Roaming\Autodesk\Inventor 2019\DesignAccelerator\Templates\CABoltCon\
The index.xml file then gets a reference to each new file's GUID with a "Node" prefix:
<?xml version="1.0" encoding="UTF-16"?>
<FDesign RecentlyUsed="C7F4D760-C82F-4ECC-8DCD-21859BD1B86D"><NodeC7F4D760-C82F-4ECC-8DCD-21859BD1B86D/><NodeCF06171C-BC49-417C-BD7D-6F7E7632E607/><Node7CEF0F17-3BFB-4FB3-B563-677F5F4A57CB/></FDesign>
The filename and part-data from one of the Bolted Connection template files
Sharing the templates should simply be a case of copying the template (GUID-named) files and the index.xml file to the relevant user path on other systems you want to share the template with.
🙂