the honey syrup is, at least on this site but I think more generally, less sweet than your substitute, inasmuch as it is honey mixed with (diluted in) water, not water and sugar (thus the syrup you added to the honey).
A bit confusingly, while the ratio of honey per water is usually indicated, I find that here it is suggested the monin honey syrup but its specifics/ratio are not described so we are left a bit to guess, which after all is in the nature of cocktail in terms of pinch/drops and yeah, ratios. But yes, I'd bet that you should have mixed your honey with water either one to one or two honey to one water if we were to follow the lines above.