Hey, I don't have the time to work on ServerlistMOTD currently, super sorry. But there is a way you can still use hex codes, it's just not super nice:

Let's say you want to use the hex code #FF0000. You have to switch # with an x and append a & to every character. It will look like this: &x&f&f&0&0&0&0Welcome 

 

You can also do gradients manually. Example from #1515db to #2bfafa:

&x&1&5&1&5&d&bN &x&1&c&6&1&e&5i &x&2&3&a&d&e&fc &x&2&b&f&a&f&ae (remove spaces ofc)

Which will write out "Nice" from a darkish blue to an aqua. You can use this site, to get the in-between hex codes: https://colorize.fun/en/minecraft

 

I know it's not nice to use but it works for the moment. :)