for anyone with the same problem...

I had the same issue as you, could not get the highlight of search words to go bold.

Found the problem to be that i had not transfered the part in links3 CSS file which makes it go bold. Thats now all done by css. So if you want the highlight to work, make sure to add those styles to your own css file if you use a different from the default.

This is the css used for highlight:

/* search highlighting */
.searchhl-1, .searchhl-2, .searchhl-3, .searchhl-4, .searchhl-5 {
font-weight: bold;
}
.searchhl-1 {
background: #ffff80;
}
.searchhl-2 {
background: #aaaaff;
}
.searchhl-3 {
background: #aaffaa;
}
.searchhl-4 {
background: #ffaaaa;
}
.searchhl-5 {
background: #aaffff;
}