Probably you'll have a better chance getting the bug fixed if you do the following:
1. You don't seem to have attached the crash report properly.
You should probably use the "Attach Files" button on the top of the page to upload that.
2. You should probably provide more information about the bug to get it fixed.
Are you able to reproduce the bug?
Does it happen frequently?
Does it happen to every server you connect?
Are you using a vanilla client or a modded client?
Are you connecting to a vanilla server or a CraftBukkit server?
Adding all chars to font.txt is not a good idea.
If you're going to be adding CJK characters to font.txt you'll end up with a font.txt containing thousands of characters.
probably getting rid of font.txt is the way to go.
As far as I know MC-3305 was originally an bug which typed wrong letters instead of Cyrillic (which probably was an LWJGL bug).
It seems though that all other issues relating to font.txt has been set as duplicate of that issue which makes it confusing.
Just came here from MC-14427.
This bug report looks to be 5 months old, but the bug hasn't been confirmed yet.
Any chance of getting it confirmed?
This looks like a similar problem to MC-7374.
Not sure why that bug report has been handled as a duplicate of MC-3305 because the summary and description doesn't look like the same problem at all.
I have checked that I can't type Japanese on signs in 13w16a.
(Just simply copy-pasting something like "これはテストです" would be enough to reproduce the problem)
Able to reproduce this with 1.8 pre1, using AMD Radeon HD 5770.