I can not replicate your issue within Firefox. Here is what I did. I click on the search button and got the following window.
I than entered the phrase "HOSTNAME
" into the the Search For box and pressed enter. This is the results I got.
Note that there are 4 pages listed in the search results.
I did install both Chromium and Midori . I went to the forum in both of them. Since I was already logged into the forum in Firefox I just went to do a search. Guess what? Both failed as in your post. After thinking about it for for a second, I than logged into the forum in both Chromium and Midori and tried searching again. Guess what? This time the results were totally different. I got the search results the same as I had in Firefox. This would tell me that the problem that you are having is not caused by the PCLinusOS website but by something totally different.
Here is the screen shot of the Chrominum search. You can also see that I did not do anything in the search box than add the phrase I wanted to search for. The results for the search of "hostname" were the same as what I received in Firefox.