My custom .htaccess commands are above the WP ones. This is working:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteRule ^$ wp-content/ahoj.txt [N]
</IfModule>

It shows the contents of my file ahoj.txt at the root of example

While this isn't working:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteRule ^$ language/ [N]
</IfModule>

As language/ is not a real directory, but a permalink set by wp (wpml). How do I make the contents of example/language visible at example without changing the URL?