It took some digging around, but I figured it out, but it's only useful if you use the working version of VERT UI for our server.. And it's relatively convoluted:
${Window[PlayerWindow].FirstChild.Next.Next.Next.Next.Tooltip} will return the string as follows:
If debuffed in ANY way: "You are weakened and cannot rest currently"
If free of all ailments: "You are not in combat and may rest at any time"
Even though these tooltips suggest it's a trigger for being in combat or not, that isn't how it actually works on the VERT UI.. It only changes if you have a negative debuff on you, whether you're in combat or not. So it will work for my purposes.
I just search the string for "weakened", and if found, cast Galadriel's every 5 seconds or so.
Yes, I know Galadriel's doesn't cleanse EVERYTHING, but it comes darn close, and even if your chain spamming it, it won't disrupt swinging / meleeDPS.
Somehow I doubt anyone else will find value in this, but figured I'd post it anyway

Cheers !