Frankly, the OVA isn't considered that "canon" for M+ valks, at least as far as Yamato is concerned. Yamato follows the Hasegawa kits, for shape, details, and markings. And the Hase YF-21 has those triangles red.
Also, the OVA's aren't that detailed. If you went by the OVA, none would ever have any markings but the US Spacy logo.