jcoa: Are Japanese developers more difficult to negoitate with than most other developers?
They sure are. Especially as GOG has a no-regional pricing, no regional restrictions stance. Japanese publishers like both regionally pricing in the US/EU and restricting access to their products in Japan. So chances of seeing any Japanese publisher other than Square Enix on GOG? Basically zero.
So while the main problem for certain titles not being available in Japan on GamersGate (while they are on Steam) is due to the language barrier -- GG has no Japanese speaking Staff, Steam at least used to (it's unclear if they do currently) -- that language barrier issue will be the least of GOG's worries.
In the case of Steam it's not all smooth sailing either as Valve needlessly further compound the issue with their misinformed stance on CERO ratings. We'd have things like the eXceed collection available if it wasn't for Valve's demands that Capcom provide a CERO rating (it's too expensive compared to the price the games sell at and totally not required for digital PC sales). That seems to be a case of Valve applying US requirements in a market where they are not needed and thus they are needlessly denying access to products in said market.
As for the English speaking skills of Japanese, you have to remember that Japanese DON'T learn English as a spoken language. They learn it as written language, as a bunch of rules to be memorized, and then only to pass entrance exams for universities. Very few actually learn English with the intention of using it as a tool for communication.
That's why there used to be an English language conversation school boom when companies started to want their employees speaking English (few companies now conduct all their internal business in English, Rakuten and Uniqlo being two examples). But the English language school boom is long since over as a result of the leading school of that market being found to be ripping off students (and to an extent its own staff), breaking immigration rules, and so forth. They were slapped with a 6 month ban on advertising and accepting new students. They never recovered, and neither did the industry as a whole, as the majority of them were pulling the same stunts.
So yeah. To sum up, two main problems for GOG:
Communication barrier
GOG's no regional pricing/restriction stance