Summado are definitely a whole alphabet trust me I was a Geeljire for 9 year and every single summad on an animal, camel, object, place has a meaning.You're right i can't say for sure we do indeed need to confirm this at the very least we need an alphabetical representation of these signs.
I thought they were writing on a tree but when i flipped the picture it was writing that it's was an inscription on a stone in somali. This is a big clue that might give credence to the theory that it's an actual somali script.
This would further expand our horizon, there are numerus summado spread throughout somaliwayne like the ones you shared. We use to think that they meant nothing but if these summado are indeed also an alphabet we might be able to decipher them and unlock a hidden part of somali history and learn about af somali.