I have been to a cave near Lake Kyle/ Mutirikwi which has Bushman paintings. The cave, called Chamavara cave has paintings which depict an Arab Dow on which baboons sit, and what looked like birds of prey (falcons?) ( possibly where the Zimbabwe bird originates from). Next to it was a large figure of what seems an important woman, she is in some form of dress that looks of Arabic origin, upturned boots, trousers and choli ( with midriff exposed).
Unfortunately, alot of this has been defaced by Mugabes Zanu PF thugs - they have written Zanu PF through it - probably because they fear the true history of Zimababwe or don't understand it.
It is thought that the Bushman may have been painting an important visitor such as the Queen of Sheeba arriving. After all, despite the Bantu theory - it has now been proved that the Lemba tribe from the Zimbabwe Ruins area have semitic blood which originates from the Levite priests in Yemen! It is highly probable that Zimbabwe was the place of King Solomon's Mines.
Maybe the hieroglyphics that you have heard of relate to the chevron patterns, crocodiles and sun discs on the Zimbabwe bird sculptures and in the stonework at Great Zimbabwe.One of the people who is more in the know on the subject is David McNaughton - a google search will bring up his work.