1) shouldn't that (why) be in the "English alternative field"?
2) the word "why" is ambiguous - I can sort of see why it would fit, IF I use a sentence like this "That's why I wrote this." Majority of the time, it just translates directly into "because". Personally, I would remove this alternative.
3) add "por qué" to spanish list - this is the "why" that forms a question such as "Why did I write this?"or "Why isn't this conjunction in the 5000 spanish word list?"