This roundel is already in-game on the su-22, though surprisingly it isn’t an available one to use as a decal for other planes
Here you can see it on the su-22 squadron vehicle (in-game):
Here it’s on a mig-23:
Here it’s on a mi-17 helicopter:
Thus, it would be logical to add a Syrian airforce roundel as a usable decal to the game, again I’m stressing the fact that it is already ON the su-22.