I would try a script approach (not really reporting, but well)
Below script is for the sys choice table, but can be a basis for the other tables.
It checks the choice tables, if translations are not available, it creates placeholder records, you can filter on, by searching for labels starting with #
Define the languaes in the array on the first line.
Hope this helps!
var langs = ['es','ja','zh']; //define languages in array
//query all english records
var gr = new GlideRecord('sys_choice');
gr.addEncodedQuery("language=en");
gr.orderBy('name');
gr.query();
while (gr.next()) {
var myLangs = langs.slice(); //clone array
var label = "#"+gr.getValue("label");
var sys_id = gr.getValue("sys_id")
//query for existing translations
var q = new GlideRecord('sys_choice');
q.addEncodedQuery("language!=en");
q.addQuery("table",gr.getValue("table"));
q.addQuery("element",gr.getValue("element"));
q.addQuery("value",gr.getValue("value"));
q.orderBy('name');
q.query();
while (q.next()) { //remove existing languages from array
var idx = myLangs.indexOf(q.getValue('language'));
if (idx >= 0)
myLangs.splice(idx, 1);
}
//insert new records for remaining tables
for (var i = 0; i< myLangs.length;i++ ){
var ins = new GlideRecord('sys_choice');
ins.get(sys_id)
ins.language = myLangs[i];
ins.label = label; // add a # prefix, to easily filter todo translations
ins.insert();
}
}
