I'll note again - if you guys are primarily interested in Cultivation multiplier spells, it is likely that Xylitemmerral will be a relatively poor source of those compared to the average lich, as he's much more kitted out for full combat. He may have spells useful in warfare or spells that present exotic attack vectors, but you haven't even learned Llewyn's yet! Trying to get both Xylite and the lich here could well be too greedy, so consider which one you value more. This is not a small decision. It may be theoretically possible for you guys to get both, but you should definitely not bank on it. The time cost of traveling to and from Xylitemmerral's siege is also not insignificant; you have already spent two weeks scamming and gathering information. Most of the information you've gathered has been on the Bleak Ravens, but most of it is also time-sensitive in one way or another.
More relevantly, even if you do manage to get to both Xylite and the Bleak Ravens lich before they are extinguished, you do not really have the BP to Beyond many spells, so the marginal benefit could end up low for what you've invested.
Whatever resolution occurs with the Bleak Ravens without your assistance might see the Lich consumed or destroyed in one form or another. You simply don't know since all you have is rumor and hearsay.
As for Consume Personally vs Give to Suizhen or Xiaoling, consider that you have a personal x6 multiplier while they only have x4 multipliers. Even without your world-striding talent they would cultivate slower than you. If you are committed to investing in your lieutenants - as you already have with Xiaoling - then the extra Loyalty the option gives is valuable as well. If you pick up more multipliers, consuming the Orb now could well very only buy you a few weeks of subjective time as your Cultivation speed ramps up again.
You could also split the difference and sell it to cultivate everyone's growth down the line.
