Never said any different. I like this translation
For if we are willfully sinning after receiving the full knowledge of the truth, there remains no more sacrifice concerning sins,
(Heb 10:26 LITV)
Not necessarily. Context and the verb being used dictates this continuous action in which you speak. Grammatically speaking V-PAP-GPM simply means something that is in a state of happening. The action can cease and never continue again. Acts 1:9 for example.
And saying these things, as they looked on, He was taken up, and a cloud received Him from their sight.
(Act 1:9 LITV)
And Mat 17:9
And as they were coming down from the mountain, Jesus charged them, saying, Tell the vision to no one until the Son of Man is raised from the dead.
(Mat 17:9 LITV)
Here is an example that contrasts both schools of thought within the same context.
But concerning the dead, that they are raised, have you not read in the book of Moses, as God spoke to him at the Bush, saying, "I am the God of Abraham, and the God of Isaac, and the God of Jacob. He is not the God of the dead, but God of the living. Therefore, you greatly err. And coming up, one of the scribes, hearing them arguing, knowing that He answered them well, he questioned Him, What is the first commandment of all?
(Mar 12:27-28 LITV)
The looking in Acts, the coming down in Matt, and arguing in Mark all ceased but the living in which Christ spoke is ongoing.
In verse 26 the writer includes himself in the start of this admonition by his use through the Holy Spirit of the pronoun "we". A better translation however might be "of us" since it is the genitive case. So Regardless what you or I think the writer definitely thought he and those to whom he was writing to in Hebrews could lose their salvation if they was willfully sinning after receiving the knowledge of the truth.
For if WE sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins, But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries.
The text says in verse 29 in the KJV "he was sanctified". Sanctified is in the aorist tense 3 person singular. Which means "he was sanctified" is correct.
He that despised Moses' law died without mercy under two or three witnesses: Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite (insult) unto the Spirit of grace? For we know him that hath said, Vengeance belongeth unto me, I will recompense, saith the Lord. And again, The Lord shall judge his people. It is a fearful thing to fall into the hands of the living God.
(Heb 10:26-31 KJV)
So we see that he (the willful sinner) was sanctified (made holy); purged. And they have done despite unto the Spirit of Grace . And once again it would fail us if we we did not note that the writer in verse 26 includes himself in the start of this admonition by his use of the pronoun "we".
Let's take a look at how the writer of Hebrews was using
G37 ἁγιάζω hagiazo (ha-ǰiy-a'-zō) v.
1. to make holy, to set apart unto God and apart (alienate) from the world.
2. (ceremonially) to cleanse.
3. (mentally) to reverence.
[from G40]
KJV: hallow, be holy, sanctify
So with that basic understanding from Mickelson's Strong enhanced we see that for something to be set apart it has to be made holy.
Prior to the writer's usage of hagiszo in verse 10:27 he sets the context to which he is speaking of in 9:13,14. Let's take a look.
Heb 9:13 For if the blood of bulls and of goats, and the ashes of an heifer sprinkling the unclean, sanctifieth to the purifying of the flesh:
The blood of bulls and goats Sanctifieth to the purifying of the flesh. Made holy on the outside: the flesh. Let's continue.
Heb 9:14 How much more shall the blood of Christ, who through the eternal Spirit offered himself without spot to God, purge your conscience (who we are; the inner man) from dead works (sin; acts that cause death) to serve the living God?
Heb 9:15 And for this cause he is the mediator of the new testament, that by means of death, for the redemption of the transgressions that were under the first testament, they which are called might receive the promise of eternal inheritance.
Not according to 10:38
(Heb 10:38 NET) But my righteous one will live by faith, and if he shrinks back, I take no pleasure in him.
Shrinks back (draws back) is in the third person singular. Which dictates that the "he" mentioned in relation to the shrinking back is the "the righteous one" (just) mentioned in the previous clause.
Incidentally how does one shrink back from being something unless they are the something to begin with.