Here is my response:
1. The English translation is not based on "probable Aramaic words" but on known Latin words. The issue here is not exclusion or inclusion, but an accurate rendering of the Latin words of the Missal, which are based on the Greek words of the New Testament. (Greek, by the way, does have articles, and there is no article associated with 'pollon' [many] in Matthew 26:28 or Mark 14:24.)
2. The Latin 'pro multis' could be "for many" or "for the many", it is true. But if "for the many" leads to the erroneous interpretation that all are forgiven because Jesus shed His blood "for the many," then those words should be avoided. While God wills all men to come to knowledge of the truth and be saved, that is sadly not going to happen, and it belongs to God's "desirous" will rather than His ordaining will. Jesus makes it clear that not all will be saved. (e.g. Matt. 7:13-14)
3. Jesus did shed His blood for the many, indeed, for all, but the words continue: "for the forgiveness of sins." The current translation "for you and for all SO THAT sins may be forgiven" is not a heretical statement (although it's not an accurate translation), because Jesus shed His blood for all of us for the possibility of the forgiveness of sins. But the new translation "for you and for many FOR THE forgiveness of sins" is also not heretical (and it is more accurate), because Jesus shed His blood for the forgiveness of the sins of many, but not of all. The Roman Catechism (after the Council of Trent) makes this clear:
"They serve to declare the fruit and advantage of His Passion. For if we look to its value, we must confess that the Redeemer shed His blood for the salvation of all; but if we look to the fruit which mankind have received from it, we shall easily find that it pertains not unto all, but to many of the human race. ... With reason, therefore, were the words for all not used, as in this place the fruits of the Passion are alone spoken of..."