Hi Antoine - welcome to the GMB
Regret I'm unable to answer your query regarding origin, but feel confident that any alcohol you consume from this decanter will not give you lead poisoning. Alcohol has been stored in decanters made from glass containing lead oxide for centuries, and since they are made specifically for this purpose - and are still being made using lead crystal - there doesn't appear any historic reason for thinking otherwise.
You will need to follow Ross' method for determining density to decide whether or not your decanter contains lead - but as a general rule if it appears heavy for its size then it will have been made with some lead content. Also, if the refractive qualities (the ability of the cut surfaces to disperse and magnify the light) are good, then this will indicate the use of lead oxide - glass containing lead oxide often appears to have a greyish or lead coloured hue.
Am sure you know that this oxide is present to improve the working open time of the plastic glass, and apparently it makes the cutting easier.
Rarely does the lead oxide content in table glass exceed 34/35%, but I think there are regulations stating it must be something like a minimum of 24%.
Attractive decanter by the way - hope someone is able to help you with attribution, although have a feeling that a lot of 'deco style' geometric pieces with black enamelling has been made over the years, so perhaps not so easy to pin down a maker.