Reply To: URL in email is incorrect
WordPress should be able to automatically update your .htacess file which it looks like it is based on the last ~11 lines of your post above. Those first ~9 lines though could be the problem as it looks like they are from another WordPress plugin or added by your webhost.
https://codex.wordpress.org/Using_Permalinks#Automatically_updating_.htaccess
If you don’t know what plugin is adding the extra bits to your .htaccess file try disabling all of your plugins except bbPress, go back to your WordPress permalinks settings and update the settings again which forces WordPress to update your .htaccess file and see how that goes.
