There is currently no way to do point/ray/hull testing against trigger entities. Associated SourceMod traceray natives make use of IEngineTrace->TraceRay() and IEngineTrace->GetPointContents() which, at least according to the implementation found here, explicitly ignore trigger entities through the use of the partition mask PARTITION_ENGINE_SOLID_EDICTS which includes "every edict_t that isn't SOLID_TRIGGER or SOLID_NOT (and static props)".

The enginetrace function EnumerateEntities() (with triggers == true) could be used to at least find triggers along a given ray/rayhull. True "collision" testing would also require the use of enginetrace's ClipRayToEntity(). Whether these two functions should be exposed directly or used in some higher-level function(s) is not important as long as point/ray/hull testing is made possible for triggers.

It is technically already possible to "find" triggers by hooking trigger entity touch events and moving some entity through a given area until they are fired, however that is not a great solution as it is imprecise and cannot be done instantaneously.