Indeed this is slightly different to the problem of voice sets. Even now, I know quite a few people who loves OFP, but cannot understand at all what the objectives of each mission are.
In the Chinese (Taiwan) community, there has been a mod that localizes the UI commands into Chinese (Move, Target, Halt, Hit the dirt etc). But that is achieved by appointing different fonts to contain different subsets of Chinese characters, then sort of encode the messages (in stringtable.csv) into the equivalent english letters. For example, A would be "Get in", a would be "truck", B would be "o'clock", and to type out "6, get in, truck, 1 o'clock" would look like "6, A, a, 1B".
This is fine (but still laborous) for the UI because it uses fixed parts of the language. But once you consider that the Chinese language, for common usage (i.e. daily usage, reading newspapers etc), uses in excess of 3000 distinct characters, and each font set provides for less than 256 (take away the numeric and punctuation) variations, it is just not practical. (We havn't even come to the problem of typing Chinese in the chat channels or the mission editor.)
With unicode support, all that problem goes away. And the game can be easily localised for sale in several other countries. Japan, Korea, China, Taiwan are the obvious ones I know.
I am a freelance translator, and a lot of my work concerns localising games. I have seen not one, but quite a few games that break when you localise it, and the original team has to go to lengths to fix it.
Rainbow Six 3: Raven Shield is one fine example. The first working patch for the Chinese version came out after the game had been released for half a year or so, and during that time, the US/UK versions have had already three or four patches. The result is that players lost interest, and the expansion pack Athena Sword simply doesn't get localised. Divine Divinity, another example, dropped out of sight in our market because part of its system was garbled up in Chinese and they couldn't fix it.
I would say if BIS is even thinking about selling OFP2 in the Asian market, the earlier programmers start taking double-byte languages into consideration, the better. Fundamental problems like displaying and inputing double-byte characters should be resolved even before the content goes to the translator.
Another problem is, the Chinese Traditional Windows systems don't use unicode either. It uses Big-5 as its default encoding. So to say it is better to support unicode is perhaps not true. What we really need, is to be able to easily switch the text display functions to display fonts that correspond to different encodings. (Which, in turn, if I'm not mistaken, allows it to support unicde, right?)
The specifics of programming is not my specialty, but I would suggest definitely that OFP2 should try to accommodate a larger character set. At least make it possible without significant alterations to the code. Then, even if BIS doesn't seek to produce localised content, volunteers will. (God knows I would love to produce localised text content for the OFP 1985/Red Hammer/Resistance campaigns, or even translate the program strings, if only I knew how.)