The diphthong "ae" is not the long e sound in Latin, it sounds like the word "eye." Your way is however, the right way to mispronounce it (i.e., it is right in the Ecclesiastical method of pronunciation) In the Ecclesiastical method, there is no difference between the e, ae, and oe sounds, and other vowels are often mispronounced although theoretically the same. It also changes the pronunciation of some consonants (like c,g,s, and x) and consonant groups (bs,bt,cc,gg,sc,su,ti) under some circumstances but not under others. These mispronunciations often lead to misspellings, which led to more mispronunciations. I much prefer the classical system, which is almost perfectly phonetic. I tend to pronounce everything in FfH the Classical Latin way (with the exception of often still using the English ch, th, and v sounds).
If pronounced classically, "Kael" is pronounced just like the name Kyle.