Nothing wrong with this verse-and yes, ALL things are become new.
Therefore ὥστε if εἴ anyone τις [is] in ἐν Christ, Χριστῷ, [he is] a new καινὴ creation. κτίσις· The τὰ old ἀρχαῖα has passed away. παρῆλθεν, Behold, ἰδοὺ [the] new καινά. has come! γέγονεν
2Co 5:17 Therefore if anyone is in Christ, he is a new creation; the old things have passed away; behold, new things have come.
2Co 5:18 And all these things are from God, who has reconciled us to himself through Christ, and who has given us the ministry of reconciliation,
2Co 5:19 namely, that God was in Christ reconciling the world to himself, not counting their trespasses against them, and entrusting to us the message of reconciliation.
2Co 5:20 Therefore we are ambassadors on behalf of Christ, as if [*Here “if ” is supplied as a component of the participle (“were imploring”) which is understood as conditional] God were imploring you through us. We beg you on behalf of Christ, be reconciled to God.
2Co 5:21 He made the one who did not know sin to be sin on our behalf, in order that we could become the righteousness of God in him.
A new creature (kainē ktisis). A fresh start is made (kainē). Ktisis is the old word for the act of creating (Rom_1:20), but in N.T. by metonymy it usually bears the notion of ktisma, the thing created or creature as here.
The old things are passed away (ta archaia parēlthen). Did pass by, he means. Second aorist active of parerchomai, to go by. The ancient (archaia) way of looking at Christ among other things. And yet today there are scholars who are trying to revive the old prejudiced view of Jesus Christ as a mere man, a prophet, to give us “a reduced Christ.” That was once Paul’s view, but it passed by forever for him. It is a false view and leaves us no gospel and no Saviour.
Behold, they are become new (idou, gegone kaina). Perfect active indicative of ginomai, have become new (fresh, kaina) to stay so.
RWP
Believe you will enjoy this commentary from a man I highly esteem.