ArniA:
There are some jdrama that have english titles, but not all. Isn't this just a matter of translation?
Those just happen to be the drama's original title (meaning, its original title is either in English or in Japanese but with English/foreign word)--what@Elite above said, basically.
To reiterate once again, if a drama does have an English title, it might mean that:
1) Their original title is in English/have English words
2) They're officially licensed abroad (on Viki, Viu, WakuWakuJapan, etc)
3) They're based on another piece of work (manga/foreign production) that does have a commonly-known English title
And seriously, given that most of those dramas are never officially licensed anyway, looking them up with their original title is actually easier.