Thanks for responding, Francois. Much appreciated. I'd come across that explanation, hence wondering why the .evt file was being ignored. If not added to Brainstorm, though, that explains it!
Please find a zip file containing an example .cnt file with associated .evt, .trg, and .sen files here.
Is there any possibility of also adding ANT/eeprobe .avr support? I have already gone through a lot of work and headaches to export all trials/conditions from ASA to individual .avr ERP files (not that the headaches were your fault!), so it would be very welcome for this project and going forward.