Fluid's definition of "Previous sibling (layer)" seems backwards
When you have a set of layers that looks like this in Sketch's layer panel:
- Group 1
  - Layer B
  - Layer A

Fluid seems to think that "Layer B" is the previous sibling of "Layer A", but that's backwards. Sketch renders from bottom up, so first comes Layer A, then comes Layer B, which means that Layer A is the previous sibling of Layer B. It looks a little counterintuitive, but that's the real rendering order.

This matters quite a bit when the layers overlap. You can't simply change the order of layers in the layer tree to match Fluid's definition without affecting how they actually render (and probably occluding layers you wanted to be able to see).
