Which Corona and displacement version + size is this? I repeatedly have issues with such "draft" geometry as well (even with less obvious problematic topology than in your case). In many projects you need all flexibility you can get, so something like booleans or extruded splines - to maintain the full stack, which usually leads to geometry that displacement simply cannot handle reasonably currently.
Unfortunately not-so-new-anymore 2.5d displacement is very very sensitive to edges and even not-so prolonged edges and sometimes I still feel like being in emperor's new cloth when it comes to Corona 2.5d displacement. A few quick options however:
- retopo the wall to proper quads or at least to a somewhat controlled subdivision with equilateral triangles at best
- subdivide like crazy (10 to 5 cm) using a subdivide modifier on top
Rapid workflow for walls like this that works somewhat ok for me would be:
- create wall, untick "edges only" in object properties to see what's happening
- do a basic retrianglulation if needed
- subdivide result (subdivide modifier) using a moderate value of about 0.5m
- do vertex paints at this stage if needed e.g. for blending materials/maps later
- model openings (extruded splines will do perfectly, flexibility here as well)
- create a proboolean out of the wall and substract the openings, set it to "Manually" in "Advanced Options" to prevent yourself from jumping out of the window sooner or later. Also set "Planar Edge Removal" to "No Edge Removal"
- if you need different material IDs later, make sure the operand has the right ones, put a material modifier on top before substracting it
- then add things like UVW map modifier, Noise or whatever is needed also as modifier or even add another subdivide modifier, smaller that the first one (e.g. 10cm)
This way you have a vital modifier stack where changes can still be done instead of having collapsed geometry which may works for displacement/AO but is baked. Screenshots: left is subdivision, right is bump with 10x10cm checker, beauty and AO. Doing the subdivision on the wall before creating the boolean out of it results in something suitable for displacement here.
Good Luck