I'm not so sure. I've done Vulcans/Romulans several times and I'd lightly grease the eyebrow ends, then cover them with a thin sheet of latex or silicone prepared in advance. It isn't hard to blend that and dust it so you can't see the edges. After that, some crepe or sable hair (take apart a sable brush for eyebrow-length hair that's almost perfect!), dipped in a dab of latex for 'glue' and applied a few strands at a time gives a nice upsweep. To finish, eyeshadow and highlights complete the effect. You have to get really close to see what was done, especially if you're careful to tuck the sheet under existing eyebrow hairs before setting it in place.I assumed the real life, production reason for the Romulan forehead appliances was to avoid having to shave a guest actor's eyebrows to make way for the upswept follicles. The rubber, instead, merely covered the real eyebrows so the performer would not look "odd" for several weeks or months afterwards waiting for his or her real brows to regrow.
Of course, it's even easier if the talent doesn't mind a quick eyebrow shave!