Thanks for that! I have read a slightly different version of this story as well in another source.
AFAIK the weapons were NOT bought by the French when the whole story was checked by the press and French public opinion calmed down.
The rumour was supposedly started by Haagens in the Eclaireur de Nice newspaper. Haagens was commercial director of HIH follow-up company HIH Siderius 1931-33. Vlessing, the founder of the original HIH by that date was no longer involved in the company.
I cannot confirm anything yet. I will deal with this story later in my book. Am working now on the first years now.