I believe that there is a mod called Omni Ocular which provides extra information to WAILA tooltips, and it does have GT6 support, so perhaps OO would be able to show the contents of the GT6 crucible in WAILA?
(You might have to read the documentation and do some manual tweaking on OO since the mod might be a bit broken atm)
(The latest XML file for GT6 is here, read the docs to find out how it works, the default files that ships with the mod might be outdated)
(I’m not sure if this specific configuration of OO can show crucible contents, but it does come with a lot of neat additions even without crucible contents)