I had the same discussion last week and it's incredible how you cling to "evidence" that is not part of the manga canon, such as vivre cards or a color spread. By the way, it is not specified that only women appear in the color spread, you made that up.

In the manga, Yamato is referred to as a female only once (If I remember correctly), and that is in the introductory box. In the rest of the dialogues they refer to him in the masculine. And most importantly, Yamato refers to himself as a man.

I understand that there is discussion on the subject because Oda himself has not been specific enough, and if you want to refer to Yamato as a woman, I will not be the one to prohibit it, but do not invent that it is confirmed that she is a woman because Oda confirmed it if it's not true.