The Steinsaltz Chumash's English translation has commentary and explanation placed between the words of the pesukim. This added text can take the form of its own clause or sentences, or it can continue the original text, as is done in the Steinsaltz Talmud.
At the start of a parashah and at changes of topic or scene, there are added paragraphs of text that provide an overview and insight.
For these reasons, it seems that one may be able to count reading the translation in this chumash as the targum in shnayim mikra v'echad targum. Would this be a halachically sound option?