In case anybody has the same problem: I made a little workaround shell script, which basically just loops over all CountryCodes, puts them in the pelias.json and runs the downloader & importer. Requires jq and the pelias docker image installed.

#!/bin/bash
for i in DE AT CH CZ;
do
        #echo "$i"
        jq '.imports.geonames.countryCode="'"$i"'"' pelias.json
        pelias download geonames
        pelias import geonames
done

Why is this has been blocked ?

Thanks @arnesetzer , in my case (Ubuntu) I had to do :

for i in FR DE NL;
do
    cat <<< $(jq '.imports.geonames.countryCode="'"$i"'"' pelias.json) > pelias.json
    pelias download geonames
    pelias import geonames
done

Ah, my bad. Forgot to convert it to a draft. The download works as expected, but if you try to import geonames It throws an expection due to a reuse of the elasticsearch config. I found this issue, but it won't change anything.