We're just speculating here i honestly don't know myself. Walaal the man clearly said he came from the lands of zaylac how can their be beja, agaw or even rashaida there? There is no single historical record that indicate their presence in these area.
Generation wise his fifth ancestor lived around the end of futuh which explains why he went to mecca al-mukarama. He was avoiding the chaos that followed after the war ended. He literally said that he can't count beyond his fifth ancestor. All he knows is that he is an caqiili jabarti zaylaci from bilad a-zayla'. Him being somali is very possible.
Walaal the founder of the dynasty is called cumar dunya hus walashama his ancestor is yusuf al-Kawneyn Here is what al-maqrisi said about this dynasty.
Know that this state was founded by people from quraysh. There're some who say they're from bani abdidar and some say they are from bani hashim and then from caqiil ibn abi talib. Their predecessor came from hijaz to the land of
jabart that we know today as jabart and it's from the land of zaylac and they settle and lived in the city of awfat "ifat" and a group of them became known for their good and piety until there were from them cumar who is said to be walashama and the heti allowed him to govern the city of awfat and collect it's tax.
The walashama literally were said by al-maqrizi to have settle the land of jabart. What would you call someone from these lands in arabic? You would give him the nisba al-jabarti just like how you would give the nismba al-misri to someone from misr also called egypt.
Yes jabarti is a slur in southern yemen but there are actual noble arab clans that are called jabarti in yemen, hijaz, eritrea sudan and egypt. Some of these jabarti families in yemen meet with somali jabarti somewhere in the family tree of caqiil. The three brothers hussain a-zaylaci, ahmed al-jabarti and the ancestor of darood somalis hashim are all descendent from ali zayan a-din.
Somali version.
Now wither this family tree is correct or not does not matter what matters is the name jabarti here isn't seen as a bad thing on the contrary it's seen as good thing.