As in the update of 10.0.0 or more, input types have been added, but one that has always confused me was the upvar. while I know how to use it, the 'script variables' block before version 10.0.0 had the slot type of 112 but now has the slot type of 14.
I can't reproduce what you're claiming, slot type 112 totally works for me, including setting all the other properties such as min/max inputs, initial slots, defaults etc. etc. and it totally does create the local variables.
yep, variadic variable templates reports a list of texts which are the labels on the blobs. We're using this inside Snap for different kinds of scope (such as the new OOP system we're working on). But you can use the extension block to declare the variables yourself: