Node ID and node title in panels page URL
Don't try to change the url with panel page manager: 

The path pattern is a way to target some page by there route. 

1 - If you want to modify the url pattern, use instead the  Pathauto pattern tool with Token. ex: /[node:title].

Once you build your pattern, it will create some alias every time you create a node, but the internal url is still /node/%node, so you have to use this one to target the nodes pages in the panel configuration. 

2- Then, if you need to use the node title in a  panel region, you can create a block view with title, and add a the contextual filter on the ID field, by taking is value frome the url.
https://duckduckgo.com/?q=drupal+8+add+contextual+filter&amp;ia=web

3- If you build a pattern like in 1 - with pathauto and token - the resulting alias will be a transliteration of the node title.