SC2Mapster

looks like you dont get it..

you create a dummy upgrade, and an ability for it.

you add the ability to whatever you have your submenu and buttons etc. on and tell the button (like your marine picture) to use ability command -> that created dummyupgrade.

with triggers you do then: "if upgradeprogress on whatever you have your marine picture on is complete" with condition "triggering progress update = dummyupgrade" then as action you execute your trigger.

that works 100% for what you need

yeah i had the same problem, its kinda weird..

i did it like creating a own upgrade, like a dummy that basically does nothing but getting researched (set time to 0 and its instant, set money like for an upgrade etc..)
after that you create the trigger like

    Events
        Unit - building research progress is Completed
    Conditions
        (Triggering progress upgrade) == Dummyupgrade
    Actions
        trigger you want to run/whatever

works pretty good for me.