Hello,
In order to achieve what you want you can use an
installer property in your "Display message box" custom action fields which can be
localized.
A similar subject is debated on our
“Translation of Error Message” thread.
Another approach is the following: you can have a message box already translated for every language, and use a condition in order to display the right message box depending the language that it has been selected for the installation.
Example:
* for English the condition can be:
*for French the condition can be:
Best regards,
Dan