Layman

First, I've studied scholars from both sides and determined that Gal. 2 likely = Acts 11. I could be wrong and the evidence goes both ways.

Second, Colin Hemer has not published any "apologetic books." That apologists have used his stuff is unsurprising because it's high quality and very thorough. Hemer was a very promising scholar whose life ended prematurely. Apologists also like F.F. Bruce but he was also a respected New Testament scholar.

Bernard Muller

Layman, this is something I modified & (in bold) added up on one of my page.
I'll run it by you:

>> B) According to Gal 4:13-14 "You know that because of physical infirmity I preached the gospel to you at the first. And my trial which was in my flesh you did not despise or reject, ... For I bear you witness that, if possible, you would have plucked out your own eyes and given them to me."
those Galatians got converted because Paul (apparently traveling on his own) had to stay among them, in their care, in order to recover from illness.
That would preclude these Galatians as being city folks of southern Galatia, the ones met by Paul (with Barnabas) during the so-called first missionary journey (as narrated in Ac13:14-14:24) and revisited by Paul (with companions) in 50C.E. (Ac16:1-6).

The most likely time for Paul's unplanned stay among (strictly) Gentiles in Galatia is when going through Galatia/Phrygia (as per Ac18:23), as "Paul took the road through the interior" (Ac19:1) on his way to Ephesus from Antioch (Syria).
The place Paul had to stop was probably a town in central western Galatia, in the viscinity of today's Bolvadin & Aksehir, on the easiest road to Ephesus, avoiding the mountains. And even if "Luke" suggested Paul had already disciples there (Ac18:23b), it is rather unlikely because no preaching was reported earlier in that region.
Let's also notice the epistle is not addressed to the Christians of one city or to an individual (as for all other Pauline epistles) but rather inhabitants of (a part of) Galatia, implying those new believers were rural people.
Also against the 'southern Galatia theory' is the fact "Luke" never used "Galatia(ns)" during the narration of Paul & Barnabas' first missionary journey. Why?
Even if the area was part of the juridiction of Roman Galatia then, it was isolated from the Galatian heartland by the dry centre of the Anatolian plateau. Furthermore, it was not occupied by ethnic Galatians, but by the people of two ancient kingdoms, the Lycaonians in the flat & arid East and the Pisidians in the mountainous West. These appellations show in 'Acts' for the first journey (13:14, 14:6,11,24) but NEVER "Galatia(ns)"!
It appears that these parts were not seen as populated by "Galatians".
However in Ac16:6, when Paul & companions move away from this region towards Troas in a NW direction, then Phrygia & Galatia are mentioned (as at the edge of Asia minor & before Mysia). <<

The first time "Luke" considered Paul going through part of Galatia, and alone, and having disciples there, and spending times then, is at the start of the third journey (Ac18:23, 19:1).
My conclusion from that:
a) The Galatians of Paul were converted then.
b) 'Galatians' was written during the 3rd journey.

Best regards, Bernard