The Celtiberian language was an Indo-European language that was spoken in the Iberian peninsula, mostly in Spain. bellow should be information (or will be) information about the Celtiberian language, such as Phonetics changes, gramatical information and etc, What is followed by "?" is either unattesed or unknown. This is mostly for prototypical popurse and not a final product, don't relly on this.
The language was written mostly with Subject-Object-Verb. In syntax, the genitive and cardinal numbers proceeded their head nouns. Adjectives might have followed a less ridge rule, since adjectives both proceeding and following their head noun have been found. Imperative verbs don't procceed everything in a syntax but come world final
This one is rather speculative, other than the Nominative singular, most are unattested but given Proto-Celtic doesn't distinguish between adjective inflection and noun inflection, one can specualte that it was the same case with Celtiberian, but none of this excludes the possibility that it was reworked by Celtiberian speakers to some degree
*φ > ∅, loss of voiceless bilabial fricative, a sound change experience with almost all Celtic languages
mn > un, "m" becomes "u" when its preceeded by an "a" or "o"
d > z(ð) this only occurs in non-initial positions, perhaps when followed by an "y"
d > t(θ) not sure on this one, perhaps when followed by an "y"
xs/ks > ss/s
gs > s
gt > kt > tt/t
ē > ei
Proto-Celtic ē > ī did not take place with Celtiberian language, therefore where Proto-Celtic displays "ī" Celtiberian has "ei", ex Celtiberian(Teiuo)reikis from Proto-Celtic*rīxs.
Note 1: Traditional transliteration use "z" for "ð" and "t" for "θ". Celtiberian didn't use different symbols for "t" and "θ"; I doubt the "d" existed, I found few words with "d"; as of now CeltiberianDēobriga and Tarvo-duro, but the usage of "d" in the former may be a Latin adaptation of the Celtiberian word given Celtiberian uses -bris not -briga, so perhaps the Celtiberian word is *Zei(u)obris. The latter is perhaps a Celtiberian name written with the Latin script, where "d" and "ð" don't exist as independent letters, possibly *Taruozuros(nominative singular of Tarvo-duro).
Note 2: "u" when it is preceeded by an vowel is the allophone of "w".