So, it might be more precise to say that observing circuмcision is objectively grave matter. 

No!  Only if the person is doing it for religious reasons would it be grave (which is like 0.001% of the population).  

I believe that we need to keep our distinctions straight.

intrinsically vs. extrinsically
objectively vs. subjectively

Removal of the foreskin is not intrinsically evil, since various considerations could justify doing it.

It's confusing to assert that circuмcision is "objectively" grave matter without any qualifications whatsoever.  This suggests that the only reason one would be excused of mortal sin would be if the person was duped into thinking it was OK, only based on mistaken reasoning.  This is obviously false.  What if there was an infection or other defect that would warrant the removal of the foreskin?  Even limb amputation is not always objectively grave matter.  There are many situations where it's required to save the life of a patient.

If, as we have established, circuмcision is not intrinsically evil, then it's the formal intent (objectively speaking) which defines its morality.  Formal intent relates to the intrinsic vs. extrinsic distinction and not to subjectivity.  Clearly, the Church teaches that any formal intent involving the observance of Old Testament ritual law entails mortal sin.  Notice that this is OBJECTIVELY.  Subjectively, someone could even on that count be excused or moral sin if, say, a recent convert was ignorant of Church teaching on the matter ... not yet having been thoroughly catechised about this particular subject.

By stating that circuмcision is always objectively grave matter, JayneK is effectively asserting that NO formal intent could ever justify circuмcision ... which is the equivalent of saying that it's intrinsically evil.  But at one point earlier in this thread, she agreed that it was not intrinsically evil.  Only subjective issues (confusions or error) could justify it.

And that's clearly false, since the formal intent of doing a medically-necessary procedure justifies circuмcision ... whether you believe that most of the reasons typically given are valid.  In the hypothetical case where it WOULD be necessary (say it's badly infected), then that would clearly justify it.  So not intrinsically evil by definition.

So, at the very least she would have to state that in most circuмstances, or ordinarily, circuмcision constitutes grave matter.  And then the debate becomes whether or not the reasons given for its medical benefits are valid or not.

At one point, JayneK suggested "double effect" as the principle to justify circuмcision.  This again rests on the presumption that no formal intent could justify it, that it's intrinsically evil.  But double effect does not apply here.  There's only one actual effect, removal of the foreskin.  I believe that she was confusing "end justifies the means" for double effect.  Take the standard example of double effect usually given, a procedure done to save the life of the mother which then ends up in the loss of an unborn child.  There might be a procedure, for instance, which helps restore the blood supply to the woman, but it also has the effect of eliminating the blood supply to the infant.  Even that procedure must be done in a very specific manner so as not to directly attack the child.  That's one procedure with two effects.  When speaking of circuмcision, there's one procedure, removal of the foreskin and the effect is ... removal of the foreskin.  But the REASONS for why this is done may vary.  I am removing an infected part of the body, for instance, vs. I am obeying God's command.  Both those are different formal intents, not two different effects.

Until the Church specifically intervenes, there's a certain amount of freedom of opinion regarding the benefits or lack thereof (of circuмcision).  It's in the realm of difference of opinion among Catholics.

When the statement is viewed within the mindset of the men, we wind up with the words of the Church meaning nothing whatsoever.

I love it when people equate their false interpretation of Church teaching as being Church teaching itself and then condemn all those who disagree with their interpretation.  St. Thomas has spoken.

St. Thomas never said it was ok to circuмcise.

He said it was not a grave sin if sought for its medical benefits, but only as religious observation.  There may be degrees of sin involved if the procedure would be unnecessary or unjustified, but here you're injecting in your own allegation, as if it were a matter of faith, that there are no benefits to circuмcision.  At no time has the Church weighed in on that particular point of science.  So you're taking a condemnation by the Church of circuмcision for the sake of religious observance as tantamount to Church teaching that it's mortal sin even if done for medical reasons.

St. Thomas never said it was ok to circuмcise.  Ladislaus, I would almost agree with your assessment above except this isn't about objective or subject reasoning.  It is about the definition of "circuмcision".  Removing diseased foreskin is not circuмcision.  It is removal of diseased foreskin and anyone can legitimately do that.  "Circuмcision" is elective surgery on a viable body part.  This is rendered null and void by the Church with an anathema attached to it and yet that is what is practiced on up to 50% of young boys to this day.  Yes, there is ignorance, but whose fault is that?  The Church says not to do it and yet the people are practicing it as a matter of course.  

in case you didn't realize, it is rude to use huge lettering to stress your same points repeatedly.
This only perpetuates your fake claims and lengthens the size of this thread.
.
You can use large lettering to quote a source since the quote box has its own issues.

Firstly, the font isn't that big.  When it was, I apologized.  Secondly, I use lettering large enough to read easily on my screen.  It is not intended to bother people.  I've defended the truth on this matter and have the Church to back me up.  You have no proof that what the Church teaches is fake.  

It is your interpretation of Church teachings that is fake news.

With millions of boys being mutilated for no reason, especially when the Church said not to, we have a serious problem.

#1) It's disputed outside considerations of faith whether there's "no reason".

#2) Church said not to do it as an observance of Jєωιѕн ritual, not as a medical practice.

... for the several dozenth time now.

You just regurgitate the same crap over and over again ... and refuse to use your brain, because you don't want to or can't or a combination of both.