How much Somali DNA does the average Oromo from hararghe or bale have ?

[NidarNidar]

No they were muslims then. They swapped religions from the 17th century to the 19th after Oromo's migrated and destroyed the Adal Sultanate. Ruling families established a new capital at Aussa in 1577 founding the Aussa Imamate after Harar's surroundings became dominated by Oromo. Civil war would soon strike between Harla and Arab factions in the imamate until Afars in the north invaded, assimilating the Harla's and exterminating the arabs.

During all of this Harar countryside was left to its own devices. Gadabuursi & Ciise were able to subdue the Oromo incursions into their territory while other clans like Harla weren't so lucky.

The Harla were probably already weakened and could never rebuild, they probably got assimilated into various Somali clans.