So to preface - I’ve been working on doing a custom theme/skin for UE4 and have come across what would be considered a random mundane report to make. Though I feel a UI Designer at Epic will feel my pain 
Specifically red nodes, more specifically, Event Nodes do not have image tinting on specifically one of the layers on blueprint nodes. This also happens to some other nodes like ‘Get Class Defaults’.
In the first screenshot - I’ve removed the gloss layer (RegularNode_tile_gloss.png) and in the bottom of the screenshot this is just RegularNode_color_fill.png alone, as you can see by the ‘Make Literal Bool’ some nodes have their color_fill layer tinted, while others do not.
I know this is hella small, don’t expect a fix - but thought I’d report nonetheless.
Thanks!