The methodology of this preliminary investigation involves the idea of translation as informational process. Most of the challenges in translation are connected with the entropy that grows all the more the wider the gap between the source and target cultures. In some cases, the gap is so wide that it makes a text seem untranslatable.  This article discusses another case of untranslatability vs translatability, which results in translating of the untranslatable, i.e. of mythology-based texts, a special type of stories where mythic allusions, personages, places and/or episodes are borrowed from the national myth lore and immersed in a plot by a contemporary author. With this kind of information we face numerous challenges of untranslatability. Meeting the challenges, the translator has to invent or discover a variety of translation tools that can help to regulate the measure of informational entropy. One of such tools is the relativity of variants that presupposes choosing compatibles rather than standard equivalents. A few types of such compatibles have been explored on the examples of Irish contemporary literature.