String Translation typo & missing translation entry in Vtiger_List_Js
See this line:
The app.vtranslate() call is being passed a string that begins with "Atleast ..." Searching the source tree files I find no language files with a string of "Atleast ...".
In fact there appears to be no string like "Atleast one field should be selected" or even "At least one field should be selected". So there is no translation for this at all.