I am a lvl 56 death in celestia and i just beat the lunarium [only because i had really good friends!] but i haven't been working in GH that much to get into wintertusk. I'm still stuck at ravenscar. Should I start working to get to wintertusk or should I keep going in celestia?
Either way will be just fine. Personally, I think Wintertusk is harder than Celestia. It's easier for some schools than others.
How about doing a little bit in each? When one gets tough or a bit boring (like fighting the same mob over and over again to collect something), go over to the other world to do a couple of things. It breaks up the tedium.
You're at a good level for both Celestia and Ravenscar, because you're able to have some of that gear with critical, plus other better statistics.
I would say work your way through WT. The drops are really good, albeit at a lower rate. Both my wife and I did WT to get to craft our gear. That has helped with Celestia a ton. The XP, graphics, and reagents are also fantastic in WT. I did not seem to have endless defeat and collect quests there as well. I am in Celestia now and am having a tough time grinding through it. Not for the challenge, just the time needed to complete the defeat and collect quests. Thinking back, I think that doing parts of each would have helped with that.