Please give me some link to the "the day in Genesis is mistranslation" I'd like to read about it, since the only thing I can find is:

http://www.mechon-mamre.org/p/pt/pt0101.htm

"ח וַיִּקְרָא אֱלֹהִים לָרָקִיעַ, שָׁמָיִם; וַיְהִי-עֶרֶב וַיְהִי-בֹקֶר, יוֹם

שֵׁנִי. {פ}

And God called the firmament Heaven. And there was evening and there was morning, a second day." (Genesis 1:8)

Which word of those is mistranslated?

Note that because of this and similar lines the Jews count the days for celebration (including Shabbat) to have a beginning at the evening (Shabbat starts on Friday evening).

If you mean "yō·wm" here are all the places where the word was used in the Bible:

http://biblehub.com/hebrew/yom_3117.htm