This article is from the Esperanto FAQ, by Mike Urban email@example.com and Yves Bellefeuille firstname.lastname@example.org with numerous contributions by others.
Although Esperanto is a planned language, it has developed well beyond
the point at which some authoritative person or group can dictate
language practice, however great the temptation may be to "tinker" with
the language. For example, many people are critical of the presence of a
feminine suffix and absence of a corresponding masculine suffix, and
have suggested masculine suffixes (-icx, -un, -ucx, -ab), neutral
pronouns (sxli, hi, ri), and/or re-interpretations of familiar words
such as redefining "frato" (brother) to mean "sibling". But there is no
single individual or committee that will simply dictate changes such as
these before they achieve general use.
Just as with any other language, the only way for such novelties to
attain acceptability is for them to be used in correspondence,
literature, and conversation by a growing number of people. If you see a
genuine lack in the language's existing stock of roots and affixes, you
may propose a new coinage and see if it catches on. Be warned that such
neologisms are often controversial and will meet with criticism in
proportion to the extent to which they break with the "Fundamento de
Esperanto" (the language's canon) or to which they are redundant to the
existing language. You should expect to receive the same reaction as if
you were proposing a new word or feature for your own language.