Is there a limmud zechus for Yidden who do not say Shnayim Mikra ve'echad targum as obligated in the Shulchan Aruch?
Answer:
This is a good question (because there appear to be many who don't do it).
The Raavan (88) writes that the obligation of Shnayim Mikra applies only to somebody who doesn't have a communal Torah reading in his community, and therefore has to make up the Torah reading by himself. In those times the Torah used to be read and translated (Targum) in shul, and those without a shul in which the Torah was read had to do so on their own.
This approach allows us something of a limmud zechus; moreover, today it is no longer the custom to translate the Torah in shul, and most people understand the Hebrew much better than they understand the Aramaic of the Targum.
Moreover, the Shibolei Ha-leket (Shabbos 75) writes that the concept of Shnayim Mikra is "worthy" but not "obligatory," and this is the general implication of the word "le-olam" that the Gemara uses for the concept of Shnayim Mikra (see Berachos 6b; Pesachim 2a; Beitzah 24b; Kesubos 8b; Nazir 23b; Kiddushin 82a, among others).
The Shulchan Aruch, however, and later authorities, all understand that this is a Talmudic obligation, and it should certainly be seen as such. Yet, the above is a certain limmud zechus on those who fail to perform the mitzvah.
Best wishes.