The foot symbol, single open quote symbol, and the apostrophe symbol (also known as single closed quote symbol) look very similar but are considered three different characters. This is why if you search for can't it will not find the word can’t, and vice versa. You can see the differences by bringing up the software keyboard on your iPad and long pressing on the apostrophe to display the other symbols.
If the court reporter used the foot symbol instead of the apostrophe symbol, or mixed and matched the two symbols, you may not get all the hits from a search that you expect. The best solution is to ask the court reporter to reformat the ASCII TXT file to only use the apostrophe symbol in the transcript.