Faithfull translation of mRNA into proteins is one of the hallmarks of life. It is generally accepted that any deviation from this pathway leads to missformed proteins and is considered deleterious per se.
A very enlightning review in Trends in Biological Sciences (TIBS; DOI: 10.1016/j.tibs.2014.06.002) shows that errors in translation are dealt with in a productive way. First of all mistranslation are obviously regulated due to species and environnement which is by itself showing that mistranslation is beneficial for the organism, at least part of it. Furthermore mistranslation is well tolerated and not deleterious for the organism. Different organisms have evolved strategies to deal with it. It seems clear that by mistranslation the organism generates alternative proteins which may help to adapt the different environmental challenges.