It really gets down to what the surfaces are like for the XC race. The Endorphin Pro isn't as squishy as something like the Vaporfly which is a big plus if you were to use it for XC.
Have you thought of lower-cushion super shoes like the Hoka Rocket X, adidas adizero pro, Asics Metaracer, or Skechers GOrun Speed Elite? Both aren't overly soft and wouldn't be super high off the ground depending on the XC course surfaces.
The only shoe I've worn for both a half marathon and XC race were the original Brooks Hyperions which were great for both (ran my half marathon PR for a win and 1-2 XC course PRs I believe). It's their version of the Nike Streak 6/7s and NB 1400s which would also be great options if you aren't looking for anything "super". The adidas adizero adios 6 would also be a neat shoe in this category, but it's a bit higher off the ground.
I would always check ebay for any shoe you can't find through an official retailer like the Streak 6 or 7. I've found 6+ shoes through there.
I'm sorry for the excessive information, but there's just so many good options haha. Good luck on the races!