 3.17.18  2:41 am are you sure? I always thought the triangle was Maj7?
i've mostly seen triangle7 to mean major7. i've also seen something like triangle b5, which means a major triad but with a b5. this helps slightly because if you just said Bb5 meaning B major triad with flat 5, that is indistinguishable from Bb power chord (root and 5). i have heard people say they think triangle alone with no 7 means major 7, but again i think it's best not to use the triangle because as you've seen i think there is a bit of confusion, and also as i mentioned earlier it can look like a circle if u scribble it too fast