Well, personally I find ĝ, ĉ, ŝ, and ĵ to be sufficiently close to the Portuguese/Tetum x, and that ĥ is close enough to k. 'X' and 'K' are, of course, part of the A-Z standard.

Even though I used the converter thingummy , my message to the Esperanto Yahoo Group came out as gibberish .

Well, that would very much depend what Yahoo! uses as its character set.

Be glad you're not typing in Chinese. At one stage they had four different character sets. It was almost impossible to send an email from Singapore to Taiwan to Hong Kong to the Mainland!