When God is referring to The or His Commandments or the Law in the NT, He is referring to the Ten Commandments and His Law. The Old Mosaic Law is done away with and has no bearing in the NT.
Col 2:16? He is talking to the Jews and believers, telling them not to let anyone judge them in keeping those things including holding the true Sabbath Day.
Romans 14:5-6 These verses do not concern any days that must be kept holy. It is referring to those recently converted, not yet having grown strong in the faith, refused to eat meat and subsisted mainly on vegetables. (Is what you said also, I agree)
I really liked your post
Blessings, Danny
In regard to Colossians 2:16, the words "ton sabbaton" or "sabbath days"; are the same words translated "Sabbath day" in Exodus 20:8 in the Septuagint.
Paul's reasoning, "Let no one judge you regarding a,
festival - yearly Sabbaths,
a new moon - monthly Sabbaths,
or a Sabbath day - weekly Sabbath
Christ, he goes on to say is the "Substance", these things were shadows.
When this passage is compared with Galatians 4:9 an obvious connection in Paul's teaching is revealed. "But now that you have come to know God, or rather to be known by God, how is it that you turn back again to the weak and worthless elemental things, to which you desire to be enslaved all over again? You observe days and months and seasons and years."
Verse 10 clearly states, "you observe...",
days (weekly Sabbaths, corresponding to "Sabbath days in Colossians 2)
months (new moons, corresponding to "a new moon" in Colossians 2)
seasons (the 7 feasts, corresponding to "festivals" in Colossians 2)
and years (the sabbatical year and the 50th year of Jubilee)
Obviously, Paul is clearing speaking about the observances of all Jewish holy days,
including the weekly Sabbath.
When God wants to refer to the whole system of Jewish holy days, rather than name them all, He would refer to the yearly, monthly and weekly as representing the whole system. SDA's argue that the Sabbath day of Colossians 2:16 is the years Sabbaths. But yearly Sabbaths were already referred to in Colossians 2:16 as "festivals." The "Year, Month, Week" pattern is well established in the Old Testament, so Colossians 2:16 does refer to the weekly Sabbath.
Yearly, monthly, weekly pattern proves it is the weekly sabbath
1 Chronicles 23:31 - Yearly (fixed festivals), monthly (new moons), weekly (Sabbaths)
2 Chronicles 2:4 - Yearly (appointed feasts), monthly (new moons), weekly (Sabbaths)
2 Chronicles 8:13 - Yearly (annual feasts), monthly (new moons), weekly (Sabbaths)
2 Chronicles 31:3 - Yearly (fixed festivals), monthly (new moons), weekly (Sabbaths)
Nehemiah 10:33 - Yearly (appointed times), monthly (new moon), weekly (Sabbaths)
Isaiah 1:13-14 - Yearly (appointed feasts), monthly (new moon), weekly (Sabbath)
Ezekiel 45:17 - Yearly (appointed feasts), monthly (new moons), weekly (Sabbaths)
Ezek 46:1-11 - Yearly (appointed feasts), monthly (new moons), weekly (Sabbath)
Hosea 2:11 - Yearly (festal assemblies), monthly (new moons), weekly (Sabbaths)
Galatians 4:10 - years, months, days (you observe days and months and seasons and years)
Colossians 2:16 - festival, new moon, Sabbath day
The order of "holyday," "new moon," and "sabbath" is a progression from the abolition of the yearly (holyday), monthly (new moon), and weekly (sabbath) Jewish festivals. Therefore the "sabbath" days does refer to the weekly sabbath. So, the plural form of the word "sabbath" cannot be used to prove a reference to merely special ceremonial sabbaths.
The Greek of Exodus 20:8-10 - the giving of the fourth commandment itself utilizes the plural also found in Colossians 2:16; Leviticus 24:8; Numbers 15:32; Luke 4:16; and Acts 13:14 do as well, but reference is made to the weekly Saturday sabbath.