Peter,
filter the modules by type.
That means: do not enter anything in the search field, select the 'filter options' button next to the search and find the 'type' dropdown.
In there, you will see:
'J2Commerce Advanced Cart toggle'
'J2Store - Advanced Cart'
I have been to your site, I saw them.
I think you are confusing the name of the module instances (which are typically named by the admin, not the developer who created the module) and the kind of module it is (= the type).
The search box does not search for the type of the module, only gor the name an instance was given.
I hope my explanations are more clear, let me know.
As far as warning messages are concerned, you will have to turn off error reporting once your site goes live, I was able to clear all warnings in the Advanced Checkout' and 'Advanced Cart' extensions, but J2Store warnings will require a code modification in J2Store itself.