While there appears to be a disjunct between Deut 29:29 and that preceding, the intent is clear - God has revealed certain things but not all.
That is, God is God and is omniscient and has revealed what humans need to know, namely the requirements of the law for obedience, peace and prosperity. Leave everything else to God.
Benson has a similar idea:
Deuteronomy 29:29. Secret things belong unto the Lord our God — That
is, the counsels and purposes of God concerning persons or nations,
and the reasons of his dispensations toward them, together with the
time and manner of inflicting judgments or showing mercy, are hidden
in his own bosom, and not to be pried into, much less fathomed, by us.
But those which are revealed — Namely, that if we rebel against him he
will pour out all these judgments upon us, except by true repentance
and turning to him we prevent it.
Similarly, Barnes observes this -
The secret things belong unto the Lord our God - This verse seems to
be added as a solemn admonition on the part of Moses, in order to
close the series of blessings and curses which he has delivered. The
sense seems to be this: "The future, when and how these good and evil
things will take effect, it lies with the Lord our God to determine;
it pertains not to man's sphere and duty. God's revealed will is that
which we must carry out." The 17th of our Articles of Religion
concludes with much the same sentiment.