In the link, it mentions that the harp for the Coat of Arms of Ireland is facing in the opposite direction than the Guinness harp trademark. It doesn't specifically say "Coat of Arms."
The harp is also the official national emblem of the Republic of Ireland and can be found on the Republic's coinage. However, there is a difference between the Irish government harp and the Guinness harp. As Guinness had trademarked the harp symbol in 1876, the Irish Free State Government of 1922, had to turn the official government harp the other way to differentiate between the trademarked Guinness harp and the official State emblem. The distinguishing feature between the two harps is that the Guinness Harp always appears with its straight edge (the sound board) to the left, and the government harp is always shown with its straight edge to the right.
In that link, another link was provided that gave more detailed information.
I guess I must make a distinction between the harp as the official symbol of Ireland (blue background, as pictured in the image above) and the harp that represents the province of Leinster (green background).