I think that lo te berti refers to something like the north pole, or the planet that lo berti is on. The definition isn't really clear, but I think that you should remove "fi".

Well, {lo se berti} is the thing that {lo berti} is north of, and Hokkaido is not north of Japan; it's north within Japan.

maybe {la xokaidos berti ne'i lo gugdejupu}?

Yeah, I don't really like the definition, because, as you say "la xokaidon cu berti lo gugdejupu" seems to imply that it is not part of Japan.

I suppose "ne'i" would work, but it doesn't seem like the most elegant solution...

gugdejupu -> pongu'e

gugdejupu is fine too.

The word "gugdejupu" is not a proper lujvo or fu'ivla.

It's an ISO country fu'ivla.

http://jbovlaste.lojban.org/dict/gugdejupu

gugdejupu -> gugdrjupu (fu'ivla)

or

gugdejupu -> pongu'e (lujvo)

It's in jbovlaste and jbofi'e parses it; I don't see what the problem is.

Complete Lojban Language, Section 4.7:

<<
Here is a simple and reliable procedure for making a non-Lojban word into a valid Stage 3
fu’ivla:
1. Eliminate all double consonants and silent letters.
2. Convert all sounds to their closest Lojban equivalents. Lojban y, however, may not be
used in any fu’ivla.
3. If the last letter is not a vowel, modify the ending so that the word ends in a vowel, either
by removing a final consonant or by adding a suggestively chosen final vowel.
4. If the first letter is not a consonant, modify the beginning so that the word begins with
a consonant, either by removing an initial vowel or adding a suggestively chosen initial
consonant.
5. Prefix the result of steps 1–5 with a 4-letter rafsi that categorizes the fu’ivla into a “topic
area”. It is only safe to use a 4-letter rafsi; short rafsi sometimes produce invalid fu’ivla.
Hyphenate the rafsi to the rest of the fu’ivla with an r-hyphen; if that would produce a
double r, use an n-hyphen instead; if the rafsi ends in r and the rest of the fu’ivla begins
with n (or vice versa) use an l-hyphen. (This is the only use of l-hyphen in Lojban.)
Alternatively, if a CVC-form short rafsi is available it can be used instead of the long rafsi.
6. Remember that the stress necessarily appears on the penultimate (next-to-the-last) syllable.
>>

{gugdejupu} is not a Stage 3 fu'ivla; it is an ISO generated fu'ivla as per http://www.lojban.org/tiki/ISO+...ural+fu%27ivla

It is in the lojban dictionary. If you have a stylistic objection, please clarify that that is the point of disagreement; if you would like other translations if the word/sentence, feel free to make them; if you don't agree with the presence of the word in jbovlaste, disagree using channels with more influence than tatoeba comments.

Oh, I guess that it is a fu'ivla between Stage 3 and Stage 4 because "gugde" still looks like a prefix.

I guess you could think of it that way, but it's not {sa'e} between them, because it isn't on the progression. It does bear similarity to a stage 3 without actually being one, though.

OK. It's ISO 3166-2 "JP" (Japan).