Okay. This is partially an issue of ignorance of language and cultural history...especially amongst people here in the USA. I know because Spanish is one of my childhood languages, and I'm pursuing my Ph.d. in African Studies so again I'm especially well informed in this matter.
First understand that there has always been a difference between the COLOR black..."negro" and Black PEOPLE..."Moro"... in the elder Iberian language. The term MORO is an Iberian Spanish phrase that at first specifically referred to Black African Islamized people. This phrase became popular due to the incursion of the Almohades and Almoravids. There was no reference to "Moors" in Japan during the time that you speak of because not only did that period predate the arrival of the Almohades and Almoravids in Iberia [ which these same Black Africans renamed ANDALUSIA or in some literature AL-ANDALUSIA ] but nobody spoke Spanish in that area either. So NO...the Japanese didn't refer to us as Moors. But since I also have family who are Japanese? I CAN tell you how they referred to us, and trace it back to the phrase 'kokojin"..."Black foreigner". I'll do so a little later cuz I'm pressed for time.
Toldja that I'm uniquely more informed about this area than perhaps many more are.
The phrase "Black" never had a negative connotation in ancient times. [ Remember even the phrase "ancient times" has varying meanings, because what might be "ancient" for Europe is certainly not "ancient" to China and is nowhere near "ancient" to Africa ]. There was no phrase or saying like "black heart". Such phrases and sayings came about centuries later only after the fall of powerful African civilizations, and the ascension of a racism so powerful and rabid that it pervaded European society so much that even European language became corrupted by it. Every day expressions began to carry the tint of racial hatred and intolerance.
Now...the term MORO is the actual Iberian term that later became MOOR in English. That term specified, as I said before, Black African Islamized people specifically at first but later came to be used for all Black people. For instance, the mighty and legendary Queen and probable Amazon Nugaymath Turquia...the "Star of Archers"...ally of King Barclay was called a Moor. She fell in one of the mighty battles against against El Cid, and her fall and El Cid's victory over her was immortalized in poetry and song.
In the West, the term MORO has become MORENO and still bears the imprint of racial identity and racial distinction. Here, oftentimes I'm referred to as "moreno" by my Central American and Boricua family and my lighter brown and White skinned kin are called "moreno claro". CLARO literally translates as "clear". There would be no need for the qualification "clear" or "lighter skinned" if "moreno" didn't mean BLACK or DARK.
Gtg but I'll be back later...