But, Joel, the equinox and solstice are not defined by climate. They are defined by the position of the sun with resulting length of day. There is nothing remarkable about noting equinox and solstice. They happen twice per year, every year.
If say an equinox takes place on date X when it is spring in present times then in the distant past when it was winter on date X due to climate change brought on by tilt of the earth's axis the same equinox would take place and would be called a winter equinox.
Besides, the changing tilt of the earth over millennia would cause a difference in the location of the heat zones in terms of latitudinal extent as well as in the apparent movement of the sun between the tropics which would as a result either shrink or extend as the case may be through the 0 degree latitudes.