Sia(j)(n) can be used for any of the third person pronouns, and only works inside its own clause, referring to the subject of that clause. You're absolutely right, "iliajn" should be reiterated. Thanks for changing it, Fred, for the sake of some confused beginner learners and the rest of us Grammar Nazis.
To be honest I had forgotten that I had written that until yesterday, then seeing the gripe, and re reading the sentence, it became glaringly obvious what error I had made.
The whole point of these exercises is to learn from our mistakes, ĉu ne?
(And even us malnovuloj who've been doing this for years, can make mistakes… it's called "being Human."
It sounds like "Kiel" rather than "Kial". I guessed why rather than how once I realised what the full question was, but "How did the chicken cross the road?" would have been a valid question. I have even read a SF short story on the subject of how chickens could try to cross a road, perhaps by Larry Niven.
Over a decade in using and studying Esperanto I have never seen transi. I have seen Trans uncounted numbers of times, I see transiri less often but it is still extremely common.
Trans is a preposition. It does not natively receive an ending, except for the rare -a or -e. Its meanings are such concepts as "Over and across." Its roots are well sunk into Classical Latin where it had virtually the same meanings.
One might find sentences such as "Li staras trans la strato."(He is standing across the street.) Trans, by itself, does not suggest motion.
In order to suggest motion, one can hang a verb onto trans. Endings such as iri (to go), or igi (to make something do something) so we find a sentence like "Li transiris la straton." (He crossed the street.) Note that the other verbs are all gone away now.
I hope that this answers your question, and has prepared you for the eventual expression like transmara (across the sea), and transruĝa (Infra-red).
This is why I have several dictionaries. If I find the word in one, I'll also want to find it in at least one other. I'm fairly constantly crosschecking words from Electronic and print collections. PIV is a good one to have, if you can read the Esperanto.
Senrata has it's uses, but you should always double check whatever you find there. Just like Google Translate.