Hi all , just an update regarding my question. I found out it's due to the importPageValue function. The processwire path sanitizer cannot create the appropriate path name and it leds to a failure of creating pages without an ascii character on the title.
$page->set($name, $value);
if($name == 'title') $page->name = $this->sanitizer->pageName($value, 2); // Sanitizer::translate
I tried appending a rand at the end of $page->name and the csv can be imported. However no matter whether I tried
$this->sanitizer->pageName(utf8decode($value), 2)
Or
$this->sanitizer->pageName($value, Sanitizer::toUTF8)
They do not work. Can anyone advise me if anything is done wrongly?
Thanks all.