In the opening verse, God rides into Egypt on a "swift cloud", which is strange imagery, but perhaps the intended idea is that the beginning of this judgment is going to be a powerful storm? In any case, somehow the Egyptians are set against each other, and once again, I don't think that "they shall fight every one against his brother" means that people will be actually fighting their own family, but rather Egyptians fighting their fellow countrymen, perhaps some sort of civil war? In the end, Egypt will have a cruel leader, and the Nile will dry up. I don't know if all of this is something that happened in the past or if we're talking about a future judgment (although the mention of "Pharaoh" in verse 11 is suggestive of the past since they don't have rulers with such a title anymore); it can be hard to tell with prophecy, which usually doesn't come with a time frame. Verse 14 does sound rather nasty, but the fact that God sends a "perverse spirit" may be another case of God reinforcing something that already exists to hasten the natural consequences. Yes, I suppose the imagery of a drunk falling over in his vomit is gross, but does being gross imply nasty language? I may not fully understand the meaning of the "Language" label in the SAB. Yes, I'll readily admit that the language of verse 16 is rather misogynistic, but once again, this is probably an outdated cultural view of women; not that it makes it right, but rather the intended audience would understand the imagery.
Now we get to a bunch of parts of the prophecy that the SAB takes issue with the validity thereof.
[v. 17] Judah never invaded Egypt and was never a military threat to Egypt.One thing I want to say about this is that I don't see anything in verse 17 that points to it being a military threat specifically; it could have been something else. It's also possible that this prophecy has yet to be fulfilled, but the fact that it says "Judah" rather than "Israel" suggests fulfillment in a time when there was such a nation, although it's within the realm of possibility that it refers to the southern part of Israel.
[v. 18] There shall be five cities in Egypt that speak the Canaanite language. But that language was never spoken in Egypt, and it is extinct now.I take issue with this, because in reality, there is actually no single "Canaanite language" (which could be something to take issue with Isaiah itself) but rather several Semitic languages spoken in that region. It's worth noting that Egyptian was not a Semitic language, but most Egyptians today speak Arabic, which is a Semitic language, and it seems to me that this may be the fulfillment of this particular aspect of the prophecy.
[v. 19-21] These verses predict that the Egyptians will worship the Lord (Yahweh) with sacrifices and offerings. But Judaism has never been an important religion in Egypt.True enough, but there are a couple things to say about this. First of all, and perhaps a less likely candidate for fulfillment of this prophecy, when I was trying to look up what "Canaanite language" meant, I found mention of the fact that during the time of the Maccabees, some Jews including the high priest fled to Egypt where they built a Temple. What I find more interesting and suggestive personally is the fact that the old Egyptian religion has been completely supplanted by Islam, which is an Abrahamic religion, meaning that Egyptians believe they are worshipping the God of Israel, and many Jews do not dispute that notion. (Historically, Jews and Muslims have gotten along fairly well, actually. I personally believe that all the Abrahamic religions are at least intending to worship the God of Israel; whether or not that means there is validity thereof is a separate question that I don't think is fit for this discussion.)
[v. 24] There has never been an alliance between these three countries, and it's unlikely that it ever will since Assyria no longer exists.To address the latter part first, the fact that Assyria no longer exists is of no consequence; if the prophecy refers to a future time, the nation of Syria plays the part of Assyria. Anyway, this is not necessarily a political alliance, but could possibly be another case of a sort of spiritual alliance, as all three of these nations in more modern times have been Abrahamic in their religions; the only problem with this idea would be why these three specifically, when the entire Middle East practices Abrahamic religion. Certainly at current there is no love between Egypt, Israel, and Syria, quite the opposite, actually! However, if you're a follower of end times prophecy, you know there are some strange changes that are coming to the world, supposedly.