In the past, I have just translated “errors of commission” with “erreurs” and “errors of omission” with “omissions”. I understand that “omission” is a type of mistake and therefore is a subcategory of “erreur”, but generally speaking, when we juxtapose “erreurs” to “omissions”, the former comes to acquire the meaning of “error because you have done something wrong”, whereas “omission” covers the things you have “left out” by mistake (i.e. the opposite). There is also a common legal phrase, “sauf erreur ou omission”, showing that the two terms are used with this particular meaning:

https://www.larousse.fr/dictionnaires/francais-anglais/sauf/70358

http://www.linternaute.fr/expression/langue-francaise/14389/sauf-erreur-ou-omission/

The two phrases work really well in English because they express contrasting concepts whilst rhyming- in French I was never able to find two phrases carrying the same (precision of) meaning and an effective figure of sound. I know that some translators like to use “erreurs par action” vs “erreurs par omission” – not sure if it would perfectly fit your context, but it would allow you to keep the rhyme and preserve pretty much the same meaning.