"I’d be happy to see more of us become the kind of PR agents who let others know what’s wrong with the Japanese scam, be they our foreign friends, ‘multi-cultural’ families or foreign reports residing in Korea." "Be they" is a way to say "whether they might be." In this case, "be they our foreign friends, multi-cultural families or foreign reports" is the same thing as "whether they might be our foreign friends, multi-cultural families or foreign reports."

That sentence is fine, except for some missing commas and that "reports" should be "reporters". Reports are documents, they can't "reside" in Korean. Reporters are people and can. :) "I’d be happy to see more of us become PR agents, of sort, letting others know what’s wrong with the Japanese scam, be they our foreign friends, ‘multi-cultural’ families and foreign reporters residing in Korea." "be they..." is a way to list things. I like all kinds of fruit, be they oranges, limes or apples. In your sentences, the word it is referring back to is "agents". "I’d be happy to see more of us become PR agents, ..., be they our foreign friends, ‘multi-cultural’ families and foreign reporters residing in Korea."

The phrase, "be they" can be understood to mean literally, "if they be" or "whether they be" Otherwise, the sentences has very awkward composition, at best. "I’d be happy to see more of us become PR agents of THE sort WHO LET others know what’s wrong with the Japanese scam, be they our foreign friends, ‘multi-cultural’ families OR....(WHATEVER....etc.) I have no idea what it means by referring to "foreign reports residing" as in: "and foreign reports residing in Korea." Reports are not usually referred to as 'residing'. People do the residing when they live in homes and apartments. .

This sounds like a comment on a forum, and has a few errors. I'll fix it before I explain it. "I’d be happy to see more of us become PR agents of sorts, letting others know what’s wrong with the Japanese scam, be they our foreign friends, ‘multi-cultural’ families or foreign reports residing in Korea." PR agents of sorts = a kind of public relations agent, but not officially. We use "of sorts" to mean that something/someone works in the same way as the real thing. be they = this refers to the "others" that should be informed. The base verb "be" plus the reverse word order create an "if" situation. You'll see this in advanced uses of the conditionals. In this case, it means "if doesn't matter if they are..."

What you are seeing is the rarely-used English subjunctive mood. Many languages conjugate verbs differently to show this mood, including English. The reality is, it is uncommon in English. The subjunctive mood can be triggered by a number of things, but for your situation above, it is used because this is a hypothetical situation. In other words, the writer used "be they" instead of "whether they are" to show that this situation is hypothetical (hasn't really happened). This is very advanced grammar that you will seldom see, and almost never hear in spoken English. Just be familiar with recognizing it when you see it, but I would not bother learning how to use this.