I also own some marbles with that "secretion" in yellow and also in orange.
However, I could not assume whether they were only made in Germany or Holland, as this type of glass or chemical in the glass could very well have used it in both parts, but it is only my opinion.
Rather I would consider it safer to attribute only to veiligglas the flame or flaming motifs like the one I show below, and also in the quality of the glass because, it seems to remember in an old thread in which Ron (wrons) mentioned an Alley machine sold to veiligglas,.... or did they want to sell it? Now I don't remember well, but I don't want to digress too much....