Request: ezee.test.yoochoose.net?mandator=723

Find all siteAccesses/contentroot for this mandator
Find all languages
export the following:

lang : eng-GB, /default lang
files : [
a.json,
b.jscon
],
lang : fre-FR, // can contain english fallback content
files : [
c.json,
d.json
],
lang : ger-DE, // can contain english fallback content
files : [
e.json,
f.json
]

And post the response json which looks like this example:
{
"transaction":"20170712184311135",
"events":[
{
"action":"FULL",
"format":"EZ",
"contentTypeId":16,
"lang":"eng-GB",
"uri":[
"https:\/\/ezee.test.yoochoose.net\/api\/ezp\/v2\/ez_recommendation\/v1\/exportDownload\/2017\/07\/12\/13\/58\/161"
],
"credentials":

{ "login":"yc", "password":"821779ae" }

},
{
"action":"FULL",
"format":"EZ",
"contentTypeId":38,
"lang":"fre-FR",
"uri":[
"https:\/\/ezee.test.yoochoose.net\/api\/ezp\/v2\/ez_recommendation\/v1\/exportDownload\/2017\/07\/12\/13\/58\/381"
],
"credentials":

{ "login":"yc", "password":"821779ae" }

},
{
"action":"FULL",
"format":"EZ",
"contentTypeId":38,
"lang":"ger-DE",
"uri":[
"https:\/\/ezee.test.yoochoose.net\/api\/ezp\/v2\/ez_recommendation\/v1\/exportDownload\/2017\/07\/12\/13\/58\/321"
],
"credentials":

{ "login":"yc", "password":"821779ae" }

}
]
}

Request: ezee.test.yoochoose.net?mandator=12345678

lang : fre-FR, // has no fallback
files : [
c.json,
d.json
]

Additionally

For update imports (when we hide, reveal or edit item) we receive also POST with itemId for edited item. But attribute lang is null always. is it possible to set the lang?