As someone who has a terrible time pronouncing certain letters in Spanish correctly (all of them), I now take time to remind you that Spanish speakers have a terrible time with certain letters in English. In fact, here’s a chart for children from a site called El Abecedario en Ingles that shows you just how hard it is:
As you can see, Spanish speakers mostly have a hard time with the same letters we do in Spanish, “G”, “H” and “J” being particularly difficult. I don’t have much problem with the Spanish “J”, probably because all of the Arabic I’ve studied has developed my ability to produce glottal fricatives to a nearly supernatural level. However, “H” and “G” habitually kick my tail, as does getting the correct accents on the penultimate syllable, or worse, getting it right when the accent isn’t on the penultimate syllable. (It took me ten years to learn how to correctly pronounce the word ejército, “army”, because I had never paid attention to the accent on the second syllable.)
The best way to sympathize with people who don’t speak English well, is to study another language yourself and labor through process of learning the alphabet all over again.