Huh?
I have no idea what you mean by the statement "There are only four Dogmas in the Catholic Church which have been enunciated as dogmas and these are the four Marian Dogmas". First off, there are many, many more (just look at the list of any doctrinal 'anathemas' by a Council) and secondly, only three Marian dogmas have been formally defined (Her Ever-Virginity has never been formally defined but it is still dogmatic).
What I meant to say is that the four Marian dogmas are unique within Catholicism in that they were ratified as ex cathedra statements. I am not aware of any other dogmas that have been declared such by an ex cathedra statement. As a result, the definition of dogma is rather hazy to people such as myself. In other threads here the question has been raised as to what the actual dogmas of the Catholic Church are and there were a wide range of answers going from the Four Maria Dogmas to all the teachings promulgated by the Catholic Church.
Also, I do not know what you mean by "there is general concensus that the Catechism of the Catholic Church is dogmatic in nature, it has never been declared to be Dogma". A catechism, by its very nature, is not a dogma but explains dogma and other teachings. There are many different Catholic Catechisms, just because the Catechism of the Catholic Church (to which I assume you are referring) is the newest (1992) doesn't make it the best or most accurate to explain Catholic teaching.
I am aware of the various Cathechism of the Catholic Church. My statement was intended to convey the meaning you expressed much more clearly, e.g. that the Catechism (containing dogmatic material (e.g. explication of dogmas)) is not Dogma in itself, nor has it been declared to be dogma (which, although conceivable, is rather absurd to consider). There are a variety of opinions regarding the current Cathechism and I am not able to render a valid opinion of my own.
"Assumption" means a "taking up into Heaven". (A logical assumption is a "taking up" of an idea). It doesn't matter whether the person has died and been resurrected or not.
But yes, you are right, there is no dogmatic definition about what happened to Enoch and Elijah, we know no more than the Biblical accounts.
But with Mary we do know because it is part of what the Apostles handed down to us.