I'm doubtful you can make the kind of creole language or culture that your looking for, at least as one group of people ala African Americans in the U.S. Language wise you have to reconcile some radically different languages, in terms of mechanics and writing. Malay is a tonal language, Japanese is not, as just as an example of why making a creole from an as diverse amount of people's is difficult The African slave trade was in general confined to a lengthy stretch of coast, this Asian slave trade is a much different beast, with targets that are more developed and different than the large majority of West African polities.
I appreciate the idea but trying to copy and paste the West African slave trade and subsequent culture that emerged out of it onto East Asia, is not going to work. What your asking for in the background ie Catholic Japan, a complete and enforced ban on both Native American and African enslavement just will not happen, the first relies too much on questionable allies and gimmicks, the second there is nothing to go stop "indentured servitude". You might be better off with perhaps a bunch of Amarillo cultures, but you would really need to be specific on where exactly are these slaves from because OTL the Portuguese made many enemies across Asia, that if their behavior is largely unchanged, I doubt anyone would be willing to engage in large scale slave trading with them.
I appreciate the idea but trying to copy and paste the West African slave trade and subsequent culture that emerged out of it onto East Asia, is not going to work. What your asking for in the background ie Catholic Japan, a complete and enforced ban on both Native American and African enslavement just will not happen, the first relies too much on questionable allies and gimmicks, the second there is nothing to go stop "indentured servitude". You might be better off with perhaps a bunch of Amarillo cultures, but you would really need to be specific on where exactly are these slaves from because OTL the Portuguese made many enemies across Asia, that if their behavior is largely unchanged, I doubt anyone would be willing to engage in large scale slave trading with them.