How to loop through to corresponding lists using xquery

I have a JSON template that I want to fill with values from two corresponding lists using xquery.

The two lists look like this:

keywords_thematic_en = ["test", "trial","error","datapool","API","REST"]
keywords_thematic_de = ["Test", "Versuch","Fehler","Datenpool","API","REST"]
keywords_thematic = {"en":keywords_thematic_en,"de":keywords_thematic_de}

The JSON template I want to fill looks like this:

{
"keywords": [
  { "value":keywords_thematic_en,"valueDE": keywords_thematic_de,"type": "THEMATIC" }
]
}

In python, this looks like this:

keywords_thematic_en = ["test", "trial","error","datapool","API","REST"]
keywords_thematic_de = ["Test", "Versuch","Fehler","Datenpool","API","REST"]

keywords_thematic = {"en":keywords_thematic_en,"de":keywords_thematic_de}

jsonSnippet = '{"keywords": []}'
jsonSnippetKW=''
for keyword in keywords_thematic["en"]:
    jsonSnippetKW = jsonSnippetKW +'{ "value":'+ keyword + ',"valueDE": '+ keywords_thematic["de"][keywords_thematic["en"].index(keyword)]+',"type": "THEMATIC" }'
    if keywords_thematic["en"].index(keyword) < (len(keywords_thematic["en"])-1):
        jsonSnippetKW = jsonSnippetKW +","
jsonSnippet = jsonSnippet[:14]+ jsonSnippetKW +jsonSnippet[14:]
print(jsonSnippet)

As a result, I get what I want:

{
"keywords": [
{ "value":test,"valueDE": Test,"type": "THEMATIC" },
{ "value":trial,"valueDE": Versuch,"type": "THEMATIC" },
{ "value":error,"valueDE": Fehler,"type": "THEMATIC" },
{ "value":datapool,"valueDE": Datenpool,"type": "THEMATIC" },
{ "value":API,"valueDE": API,"type": "THEMATIC" },
{ "value":REST,"valueDE": REST,"type": "THEMATIC" }
]
}

Trying the same using the JSONTemplater and xquery, I only get so far for looping through one list:

for $Keyword in fme:get-list-attribute("KW_themaic.KW_de{}")
   return
   {
      "value": $Keyword,
      "valueDE": $Keyword,
      "type": "THEMATIC"
    }

How do I set up a for loop with xquery, looping through the two lists and insert the corresponding values?