No, you haven't. Such a distinction is arbitrary, since the covenant of Sinai was all given through Moses, the lawgiver (John 1:17). It's arbitrary to separate Exodus 12 from Exodus 20.
and end time prophecies say that they will be observed by all nations when Christ returns. How would you address that issue?
Since I'm not a dispensationalist I do not find anything in the old testament about "Christ's return" and a turning to bloody, old covernant feasts.
All the feasts pointed to Christ's coming into the world to save sinners by His blood atonement. The feasts have been fulfilled because Christ has come and "fulfilled all righteousness." Anyone looking to a future keeping of old covenant sacrifices is simply denying the sufficiency of Christ's work on the cross.
Well you're mistaken on a major issue. Notably on your statement that all of the coveant of Sinai was given through Moses. The ten commandments were spokenn directly by God to the people....completely unmediated by Moses (Exodus 19:1, Duet 10:4)
Do you believe that everything that occurs in the collection of books we call "the old testament" is part of the old covenant that God made with Israel at Sinai? If not, then where do you draw the line?
Since I'm not a dispensationalist I do not find anything in the old testament about "Christ's return" and a turning to bloody, old covernant feasts.
You don't believe Christ is going to return to earth?
Zec 14:3 Then shall the LORD go forth, and fight against those nations, as when he fought in the day of battle.
Zec 14:4 And his feet shall stand in that day upon the mount of Olives, which [is] before Jerusalem on the east, and the mount of Olives shall cleave in the midst thereof toward the east and toward the west, [and there shall be] a very great valley; and half of the mountain shall remove toward the north, and half of it toward the south.
You don't think that this describes the return of Christ?
Zec 14:16 And it shall come to pass, [that] every one that is left of all the nations which came against Jerusalem shall even go up from year to year to worship the King, the LORD of hosts, and to keep the feast of tabernacles.
Zec 14:17 And it shall be, [that] whoso will not come up of [all] the families of the earth unto Jerusalem to worship the King, the LORD of hosts, even upon them shall be no rain.
Zec 14:18 And if the family of Egypt go not up, and come not, that [have] no [rain]; there shall be the plague, wherewith the LORD will smite the heathen that come not up to keep the feast of tabernacles.
You don't believe that what is described above is a future event? If not, how do you explain it?