Google’s ranking choices are often a mystery. In this case, I imagine it’s because your actual title and text on the site itself don’t match the “mindanc” text.
For example, searching “minda naib uitm” does show actual pages as the first results. If you’re expecting searches with the text “mindanc” to match, you’d probably want to have that in your page title or headings somewhere.
It would depend what’s happening specifically with the two sites, but I do think it’s really down to the fact that what you’re searching for is in the URL but not the actual text much. The XML file has a bunch of links in it, so it contains that part of the URL a lot.
I doubt that using Omeka 2.7.1 on one site and 3.0.1 on the other is the important difference here.