The problem is you are only looking at what it seems to you that Protestants are doing wrong and don’t look further back in the process, at what Catholicism is doing.
The Protestant arguments against certain Catholic beliefs have become “doctrine” of a sort, but for the most part they are actually just objections to the extremes and unwarranted certainties of Catholicism.
Take, for instance, the question of whether or not Mary knew Joseph and had more children, or remained a virgin. Protestant counterarguments come in because of, first, the Catholic claims of certainty on the matter, but then, even moreso, because from that one claim Catholicism has added more and more “certainties” to the point of raising Mary to the level of an idol. That, in turn, has radically re-drawn the Gospel in Catholicism, to the point that Mary is “co-redemptrix.” If Mary wasn’t so over-emphasized, to the distorting of the Christian faith in all sorts of ways, then evangelicals wouldn’t so vehemently counter the Catholic dogma that Mary was a perpetual virgin. For is the belief that Mary *did* have children some major theological doctrine, up there in importance with fundamentals like the inerrancy of the Bible, Jesus’ blood atonement, and His resurrection? No, it isn’t.
Now, I know you won’t agree that Mary is an idol in Catholicism, and you’re welcome to say whatever you want on the matter, but I’m not interested in going over all the issues point by point here. I’ll just present what I’ve concluded on it. Catholics know the differences between God, and creatures, and idols, but the abstract knowing doesn’t mean they haven’t made her an idol. Muslims say they’re monotheists yet they seem to make both Mohammed and Muslim men in general into idols/false gods. According to the ability that God has given all humans to understand and discern the spiritual, Catholicism worships Mary, and the claims of distinctions between how they treat God and Mary are like legal technicalities to cover that up. Then there are the claims that Catholics do but don’t pray to Mary, that praying is just asking, the prayers are just for intercession, and people ask other people to pray for them, and so on. I’m not satisfied that any of these claims hold any water whatsoever. I’ve looked into them and read the various prayers to Mary, which include professions of dedicating oneself completely to her and calling her Healer, as well as well as the Catholic’s life, sweetness, and hope.
On Revelation 12, then, I would say first that it is of course impossible to read it without thinking of Mary. That is why, I would also say, that it offends you if someone says, no, this passage is about Israel. It seems to deny the obvious - isn’t that your point?
Yet again, though, the real problem here is the Catholic seizing on this passage to support Catholic teaching which has built Mary into an idol over the years, in essence where Scripture gave an inch a mile was taken. And the Catholic way to examine such questions now is to hold Catholic teaching before all else, to cherrypick from the Bible when it helps, and to twist and deny whatever is in the Bible that doesn’t help the Catholic teaching cause. The Bible is therefore made the slave of Catholic teaching, merely there to lend support to Catholic teaching.
And it’s the case with the woman in Revelation 12. The passage is of course related to Mary, but exactly how? And just because it is, doesn’t justify all the various claims that Catholicism makes that aren’t warranted about Mary, as they exceed what’s been revealed while also contradicting Scripture. But to continue with Revelation 12, yes, it speaks in a sense of Mary, of that I have no doubt, but it is also not quite Mary, either, and as others have pointed out, it also speaks in some ways of Israel, as well, and there could be other possibilities too - like, for example, the birth of Christ Himself within each believer, and how Satan tries to destroy Christ within us once He’s been born there.
Like “a father sacrificing his son” can speak not only of God the Father and God the Son, but also of Abraham and Isaac (as Abraham did entirely yield his son to God’s will, although Isaac wasn’t killed), and how Joseph adopted Jesus, so that God could adopt us, who aren’t His children, God often uses the same spiritual figure in different ways to accomplish His objectives.
Then note that in Revelation 17, there is another woman talked about - the whore of Babylon. And what is her identity revealed to be? “And the woman which thou sawest is that great city, which reigneth over the kings of the earth,” (17:18). So she wasn’t a woman, actually, but a city - perhaps. Again, “Babylon” might very well not even be Babylon. From Revelation 11, too, which tells of the Two Witnesses: “And their dead bodies shall lie in the street of the great city, which spiritually is called Sodom and Egypt, where also our Lord was crucified.” So Jerusalem, spiritually, is “Sodom” and “Egypt”! Revelation reveals such relationships between things and people, but much of it, too, isn’t fully explained and revealed, but only gives us glimpses of the truth for now.
And again, the thing about Catholic interpretation of Revelation 12 is that it is about affirming Catholic doctrine, which overstepped what was revealed to begin with, to created doctrine that contradicts God’s Word and distorts the fundamentals of Christian faith, chiefly by making Mary into an idol.