No text recognition software can deal with all the different outlines, warped perspectives and cursive characters that SFX is displayed as.
Use Pleco (on your phone) or LINE to stroke these SFX characters by hand (one-by-one, but it doesn't take long). Pleco is by far the best. These stroke recognition programs are pretty generous with bad drawings, and they give a pretty good list of possible matches for you to choose from.
Then just search the character and use its pinyin form for the translated SFX.