hello99: “I think the Rashba knew minhagei Sefarad as well, and he writes that they did NOT wear tefillin. Remember the Beis Yosef left Spain 5 years old while the Rambam was born and raised there and only move to Egypt later in life. The fact is that anyone familiar with minhagei Sefarad knows that they do NOT consistently follow the Rosh, who only moved to Spain after his children were grown and married unlike Marcus Lehman.”
The Rashba lived a long time before R. Yitzchak Karo. R. Karo described the matzav he saw and knew, and he says they followed the Rosh. Do you know better than him? Were you there?
Re the Rambam, the point is where he wrote his seforim, not where he lived as a youngster. He wrote the Mishna Torah in Egypt, long after leaving Spain.