Seems Serbian guys was very proud of the recognition of their French allies and Croix de Guerre had a high value for their contribution in WW1.
And by that I mean also the authorities as its was by law regulated what you wear where on a medal Bar (more or less, of course you always have exeptions from the rule).
Thus,from the rare examples of Medal Bars that I saw with Croix de guerre, French cross comes after the Orders,first of all the war crosses, even I saw a picture of King Alexander I wearing his Croix de guerre after Orders and Milos Obilic bravery medal and then the rest of the medals (some 7-8).
Also General Zivojn Misic was wearing his Orders and Breast II class orders and from medals, proudly only his Croix de Guerre.
From all these, I can imagine, what this cross ment to them back then, they wear their French Cross very proudly....