Your English is pretty much perfect - no barrier. I just wasn't sure what you meant.
There's no way to test if the volt file will generate the HTML the author expects. But there is a way to test if the file will compile.
There may be a simpler approach, but how I would do it is with a SimpleView service. When the user saves the view, save the Volt syntax to a temporary file. Then, try to render it with SimpleView. If an exception is thrown, then the syntax was invalid.
I don't know if SimpleView will generate notices and errors in addition to Exceptions, but if it does, you can use
set_error_handler() to convert notices & errors to Exceptions - like the first example here: https://www.php.net/manual/en/class.errorexception.php