I can't get my head around app issues but let's talk search issues and a possible alternative for you.
Our vBulletin software usually gives me the most focused results, but it has its quirks. Foremost is that search results are muddy if you use more than a single search word. So I just have to do separate searches on candidate search words. The power comes in when you have half an inkling who might have posted the info you are seeking. I always use advanced search for this reason. This isn't that useful if you are doing a cold search without knowing previous useful postings on a subject. Yep, I've been around too much... Somewhat less powerful filters in advanced search are the ability to restrict it to a specific topic subforum or appearance of the keyword in titles or posts. And yet sometime that can make all the difference. Your results may vary...
Does Google function well for you? I knew that Boondocker had posted on this and I used vBulletin advanced search to find it -- Google search as suggested by TomW
. You can use single words, multiple words, "exact phrases" by surrounding in quotes, or combo of "exact phrase" + word(s). Results tend to be numerous, a bit unfocused and it takes some reading to figure out why that search result kicked out.
I've heard that this issue exists. Beyond that, I don't have a clue about chances for search to be coded into apps.