en.wikipedia.org
@Som
The first and most important split in LE Cushitic is between the Saho-Afar vs everybody else.
This to me suggest that the very first LE Cushites likely lived around Harar-Jigjiga. Roughly where Afars, Oromos, and Somalis coincide.
Subsequently, all those other ones (including Oromos) can then be explained by movement from the arid East (Somaliweyn) towards the more fertile West (Southern Ethiopia). It makes more sense migration went that way.
Nomadism erased linguistic diversity in Somaliweyn. If Somalia had a similar climate to Southern Ethiopia, we would see much more LE Cushitic linguistic diversity in Somalia. I doubt people in Djibouti and Kismaayo would be able to communicate then. So relying on linguistic diversity is iffy.