I think the problem with words like teeanager or Dekkelkjarulo is that they refer to a meaning that is unique to the specific language. In this case, it refers to how numbers are said. Teenager refers to thirteen through nineteen being the only ones ending in "teen", Dekkelkjarulo would refer to 11 to 19.

Adolescent (or its direct translation in any language) which by definition refers to puberty and maturity with no distiction of age (as some may be early and some late and the maturity part can evolve with cultures) is likely a better choice of word as far as describing a specific person (doesn't have to be your own child) were infanoj, or the french enfant refers to one's child from birth to death.

Actually, this whole discussion is pretty theoretical anyway. I don't ever hear any of these words used - dekumjarulo, dekkelkjarulo, adoleskanto. The stages of life, as most people speak of them in Esperanto, are bebo - infano - junulo - plenkreskulo.