So, looking up this topic, it looks like this has been something that's been "in the works" for YEARS 

Any ETA on when we'll have variables available in resolution templates the same way they work in reply templates? 

This doesn't seem like a big ask to have to wait so long for 

https://pitstop.manageengine.com/portal/community/topic/variables-in-reply-template

https://pitstop.manageengine.com/portal/community/topic/variables-not-available-in-resolution-template