Alphabet

While Jel does not appear to have a native written language, how it is written in-game gives us some insight into its phonology.

A	Variously pronounced as [a] or [æ].
B	[b] — Fully voiced.
(C)	Only attested in one word, which is also the only non-hyphenated word that contains two /k/ sounds. Therefore likely written as C there for aesthetic purposes, as both instances are pronounced the same.
CH	[tʃ]
D	[d] — Fully voiced.
E	[ɛ].
EE	[i]
EI	Likely not a diphthong, given a lack of others in the language, and ample room in the vowel space. Invariably pronounced as a monophthong [e].
F	Only attested once in writing. Probably pronounced [f]. Likely only appears in onset position.
G	[g] — Fully voiced. Never [dʒ].
H	[h] — May appear in either onset or coda.
I	[ɪ], except word finally, in which it is pronounced [i].
J	[dʒ]
K	[k^h] with noticeable aspiration.
L	Pronounced as a "dark L", [ɫ], in all positions.
M	[m]
N	[n]
O	[ɔ] — Possibly lowered to [ɒ] immediately following a vowel.
OO	[ʉ]
P	[p^h] with noticeable aspiration.
R	[ɹ]
S	[s]
SH	[ʃ]
T	[t^h] with noticeable aspiration.
TH	[θ] — Only unvoiced attested.
TL	[tl]
U	Free variation between [ə] and [ʊ]. [ʉ] word-finally.
V	[v] — Only appears in onset position.
W	[w] — Only appears in onset position.
X	Pronounced [z] in onset position, and palatalizes to [ʃ] in coda position.
XH	Pronounced [ʒ] in onset position, but pronounced as an affricate [ks] in coda position.
Z	[z]

Grammar

There are few Jel utterances attested. However, some inferences can be made:

Jel lacks tense. It may have a roundabout way of indicating aspect by utilizing words and prefixes indicating "old" (potentially an), "becoming" (such as uvas~), as well as "young", "new", etc. Instances such as this are almost unattested, and those examples that do exist refer to very distant or uncertain times, so it is likely that these terms are scarcely ever used in casual conversation, and verbs can generally be considered to be happening in the present if they are capable of being remembered or contemplated.

Word order is highly flexible, to the point of great ambiguity. For instance, bok-xul "bowl of death", has its head as the first word in the phrase, while vakka-bok, "bowl of the sun" has its head as the final word.

There is no grammatical difference between an agent and an action. Once again, this likely leads to great ambiguity in the language, so it is likely that the head of a phrase is indicated through nonverbal means. I believe that this is the difficulty or impossibility of true fluency in the language for all but Argonians that is referenced several times.

While there is little inflection in the language, verbs are noticeably inflected in some circumstances. Due to the unlikelihood of this inflection being for tense or gender, and a lack of noun inflection, it seems likely that verbs inflect for person.

Jel thrives upon idiom and metaphor. It is difficult to speak effectively without fluent knowledge of Black Marsh culture and geography.

U Hist-greel kota norg-xeech.
be Hist-enemy black warning-seed
"The enemy of the Hist is/will be a black forbidden seed."

Ruheeva u xul-vahat!
meet be death-taboo
"This meeting will be (your) grave!"

Waxhuthi! Norgsa oj!
damn_it! warn-1 2
"Damn it! I'm warning you!"