Precisely speaking, transliteration is conversion not to another alphabet, but to another script. Polish alphabet is within the Latin script, so you can not transliterate it to Latin - the same as you can not transliterate French é, à, è. You may see also here. But, you can transliterate, for example the Greek, Russian or Japanese alphabet to Latin script.
He was very clearly just asking how you would write ł using the sounds of English ("For example: œ is oe, ü is ue, æ is ae, etc. ). Instead of just saying "it's like w in English," you just kept on telling someone who was struggling for the right word that he was wrong without trying to offer information that he could learn from.
Perhaps you want to know how that letter sounds?
No, it is standard. In "jabłko" the letter "ł" is mute and "b" is devoiced and pronounced as "p", see http://sjp.pwn.pl/szukaj/wymowa+jab%C5%82ko
For devoicing in Polish, see: https://en.wikipedia.org/wiki/Polish_phonology#Voicing_and_devoicing or better here in Polish https://pl.wikipedia.org/wiki/Ubezd%C5%BAwi%C4%99cznienie
May I recommend SwiftKey, you can put 5 languages on it so you can for example have English, German, Spanish, Italian and Polish at the same time. Including the special characters.
But anyway, the answers without Polish characters should be automatically accepted. I don't like it, I think typing without special characters isn't much of learning, but I know people do it. So "Mam jablko" (with a normal L) should have worked.