Most Juhaku fanfics worth reading are on Archive of Our Own. There are some on Tumblr as well, good luck finding them (I don't think that there's a specific tag for jh fanfics). Those posted on other websites (such as ff.net) are usually crossposted from ao3. These are of course in English. You can find the foreign treasures yourself.
Judal | Judar/Ren Hakuryuu
Here's the ship tag on ao3. Note that some fics have not been tagged with the ship tag but just the charcters.