Funnily enough I am also on a client job at the moment in which I am forced to use Boolean Operations, but unlike you, I can't go back for better STEP reference 🙂
I am getting things to work with a rather assorted variety of tricks and bedevilment, some of which seem to have no reason behind them whatsoever, yet *touch wood*, I do find myself winning most of the boolean battles I face.
In short my top boole tips are:
Do anything you can to avoid using them at all. But if it is unavoidable...
Aim for a solid boole first, so you get the inside of say carved lettering, but if that is not possible, for example if one of your source meshes is open, then still do the boole, but you will only get an intersection, and have to model indents yourself from that outline, which is still helpful.
Make sure the mesh you are cutting into has regular, even distribution of polygons and enough density.
Always break the phong shading along intersection lines
If things go invisible...
Move the source geo slightly.
Move the other mesh slightly.
Change the interpolation in any spline based geo to uniform / natural, and vary subsegment numbers
Have all the options in the boole object ticked to start with...
If that fails, turn off HQ, but then set and use proper phong edge breaks.
Better to turn HQ back on, and instead change the topology of the source meshes until it doesn't fail any more. This can be as easy as sliding 1 vertex or as complex as re-topologising an entire section, but if you are patient you WILL find something that works...
Spin edges to avoid counter-flow junctions and complex poles.
But not if it's animated booleans. That sh1t is just not predictable or reliable and there's really not much we can do other than find another way 😉
CBR