To learn how to adapt names into unofficial words, first you have to know how toki pona’s phonology works. The language’s words consist of a series of syllables assembled under a ©V(N) system. This means that each syllable consists of an optional consonant, then a vowel, then a nasal (the “n” sound).
In addition, the sequences “ji”, “ti”, “wo” and “wu” turn into “i”, “si”, “o” and “u”.
Here’s a table of all possible syllables.
Another rule is that you can’t follow a vowel sound by a vowel sound, and you can’t follow a nasal “n” sound with an “m” or another “n”.
Consonant sounds that don’t exist in toki pona are replaced with similar sounds. For example, Rome (Roma) turns into “ma tomo Loma” and Jakarta turns into “ma tomo Sakata”.
|consonant||sounds it can represent|
|k||k, g, sometimes h, French r|
|n||n, syllable-final m|
|p||p, b, f, sometimes v|
|s||s, z, j, ch, sh, zh, ts, x|
|w||v, w, sometimes r|
To deal with several consonant or vowel sounds in a row, you can either remove one of them or add an extra one.
For names of cities, it’s best to use pronunciations that people in that city would use. For example, the city of Toronto, Canada is transcribed in the official book as “ma tomo Towano”, not “ma tomo Tolonto”.
Names for countries can be derived from the genitive case or the forms used to refer to their country’s people or language. For example, the native name for Japan is pronounced “Nippon”, but the one for Japanese people and the language is “Nihonjin” and “Nihongo” respectively. The latter two are used to create the unofficial word “Nijon”. Similarly, the name for Sweden is “Wensa”, derived from “Svenska” (“Swedish”).
A rule some people use is that, if the resulting unofficial word sounds exactly like a native toki pona word, then the unofficial word is modified. For example, the name “Mary” (from which “meli” is already derived from) is typically turned into “jan Mewi” instead.
There are other rules, and interpretations of them differ. The “o kama sona e toki pona!” course features this list of rules, and the official book has its own.