I am thinking that the 2 major, 1 minor rule doesn't quite work as
people can collect all the minors and discard most of them. I am
thinking calamities should work this way:

3 calamities maximum allowed, in those 3 calamities, you can have any
of the following combinations:

2 majors, 1 minor
1 major, 2 minor
3 minors

any more than this are discarded. I also think if you have an advance
that aggrevates a calamity, you can't discard it.

Also, we used to play with an old civ rule that you can't be reduced
below 16 unit points no matter what, which will save some people from being completely wiped out by calamities (even with the limit, this can happen with secondary effects).

any thoughts?

I've been thinking on calamity limits a bit too. My favorite scheme is this:

a) If you have two or less major calamities, you are hit with all your major calamities.
b) Otherwise begin by discarding all duplicates.
b1) If you have both major non-tradable and major tradable calamities, you'll get hit by one random calamity of each type.
b2) Otherwise you'll get hit by any two random major calamities.
Then you'll get hit by minor calamities until you have got hit by a total of three calamities.

That scheme is similar to your. but also takes the difference between tradable and non-tradable calamities into account.

I don't like the rule that aggravated calamities can't be discarded, that just makes the civcards unbalanced, and you still have to consider the case when you have three aggravated calamities.

We've been running this just as a AdvCiv game (no CivProject), but I've been particularly fond of Zeno's Painted Porch (stoics variant), where all calamities are tradeable, but there is no limit on calamity cards damaging you. It actually seems (to me being the GM) to have increased the money in the game.

Now, back to your question. I'm pretty sure the CivProject rule book has a line to the effect of making no mention of calamities during the trade round. This makes it awful hard to do what you suggest.

Actually, it doesn't. AdvCiv rules states that you must name two commodities in a trade trade, and in an appendix it states that you can't mention calamities during trading. CivProject rules, however, states that you must name two trade cardsin a trade, and doesn't mention mentioning calamities.
However, neither with the current or proposed rules would there be any benefit in buying minor calamities (though there could be instances where it would be worth it to buy some lower level major calamities, i.e. when you have fundamentalism and regression).
The problem I've noticed, and I think alloowishus has to, is people who are giving all their major calamities as third cards, and end up with only three minor calamities. In all fairness they should get hit with all three, but get away with only one.

Though I think it is a wonderful game and still enjoy playing it after 20 years, one of my big criticisms of the game is that once an Empire gets ahead, it generally stays ahead.

Helping it to achieve this is the fact that the leading Empire can generally buy Civilization Cards to offset the damage from the Calamity Cards. It also (usually) has more cards to use when trading away Calamity Cards to poorer smaller Empires.

In Expansion Rulebook_2.07 it states “24.3 No player may be the primary victim of more than two major and one minor calamities in the same turn.”

To increase the difficulty for larger Empires we play the following (home) rules:

“24.3A No player maybe the victim of more than four major calamities and two minor calamities.

24.31A Any player may be the primary victim of 2 minor calamities. If the player receives more than two minor calamities in the same turn their minor calamities are shuffled together, and two are drawn at random. The remaining minor calamities received by that player are disregarded and are returned to the appropriate stack of trade cards.

24.32A A player who has 0 – 3 cities may not be the primary victim of more than two major calamities and two minor calamities.

24.33A A player who has 4 – 7 cities may not be the primary victim of more than three major calamities and two minor calamities.

24.34A A player who has 8-9 cities may not be the primary victim of more than four major calamities and two minor calamities.”

24.35A If the player has more major calamities than their quota, the major calamities are shuffled together, and the number of major calamity cards as outlined above are drawn at random. The remaining major calamities received by that player are disregarded and are returned to the appropriate stack of trade cards.

Any comments, criticisms or suggestions are more then welcome.

Our group has the following rules:
1. No player may be hit by more than 2 major calamities, or 3 total calamities
2. No player may be hit by more than 1 non-tradeable calamity
3. If a player has both tradeable and non-tradeable calamities, they must be hit by one of each.

We actually haven't gotten enough people together yet to add in minor calamities, so we haven't playtested that part yet.