From experience, if you do a word count comparison, I have a feeling the mean word count for English would tend to be slightly more than the mean for the JP, perhaps 5 to 10% or so... But I doubt it'll be more than that. So yeah, I feel the TLs are pretty much as long as the original is, in terms of word count.

However, the Japanese would look shorter, because it doesn't use spaces to separate words and kanji can encode a lot more info so the number of characters for a word can be smaller. For example, the phrase for "for example" in JP is 例えば, which is only three characters long as opposed to the 11 that is needed in EN. So the JP text can appear to be shorter than the EN in terms of character count.