"When Adamo told Sofia about the terrible animals, she was afraid."
Translation:Kiam Adamo rakontis al Sofia pri la teruraj bestoj, ŝi timis.
Apparently it's fine used nontransitively - or I guess transitively with an implied/elided object.
https://eo.wikisource.org/wiki/Malnova_Testamento_(Zamenhof)/Psalmaro/27 has "Se elpaŝos kontraŭ min armeo, Mia koro ne ektimos"
Timiĝi strikes me as ok, too, but emphasizing that you're becoming afraid. (then again ektimi is clearly inchoative, too, so idunno what the difference in meaning between those two might be exactly; maybe ektimi is more abrupt)