Hi
first, look in your .htaccess and find this:
RewriteEngine On
remove the # in front if needed
Then find this:
## Begin - Custom redirects
And add those below just after
for the "detail" you can start with this:
RewriteRule ^(.*)-details\.html$ /$1.html [R=302,L]
Then check the results, once all is fine change to:
RewriteRule ^(.*)-details\.html$ /$1.html [R=301,L]
(302 tell the bot that this is temporary, 301 that's permanent)
For the "/MENUSLUG/examplecategory.html" if the old link (/examplecategory.html) is not naturally generated by the website, so you're facing an alias, the natural way should be to redirect the old link to the new one.
So as Pinochico said, you must first check if the canonical link is really like "/MENUSLUG/examplecategory.html" before making any choice.
But to redirect the categories in one way or another you can use:
RewriteRule ^MENUSLUG\/(.*)\.html /$1 [QSA,L,R=301]
other way
RewriteRule ^(.*)\.html /MENUSLUG/$1.html [QSA,L,R=301]
To do some tests you can look at the network dev console of your browser or use this one:
https://www.redirection-web.net/