English translation should be easier since English has a way smaller font collection than Chinese...
So if Chinese tranlation becomes possible, than theoretically, so would English
Nope. The Chinese (and Korean) have it easier since the Japanese font already has all or most of the hanzi they need, in the correct size.
English translations must use at the very least a half width font (if a variable width one isn't possible) so that THE TEXT DOESN’T LOOK UGLY AND POSSIBLY TAKING UP TOO MUCH SPACE AND FILLING UP THE SCREEN TOO QUICKLY.
English translations use more characters than Japanese scripts, and the engine must account for that and not crash if there are more than 18 characters per line or so. Or have memory issues because the text can only use dual byte characters which can cause the RAM to fill up too quickly and the game... to crash.
The font must include English letters or be possible to edit (both the graphic and the width) to include them if they're missing.
Most Japan-only games (even Nintendo games, no less - exceptions exist like Level-5 games) don't give a damn about this stuff. Some are even delayed (Tales of Graces) or cancelled (Lifesigns 1 DS) because of this even when the company wants to localize them.
But they're still good enough for Chinese fan-translators.
They only have to edit the text.
They could also try to edit the graphics with text but it's not that big of a loss if they couldn't since some kanji are easily recognizable in both languages.
The actual hard part if the font is optimized to English/small kana, 8 pixel width letters and the like. For those cases they really need to do reprogramming effort similar to what some English/latin-language fan-translators do when facing up the above mentioned cases.