Illyricum did not exist as a province after the reign of Vespasian. 2 Timothy was written in the second century AD, at a time when illyricum did not exist anymore and was replaced by the provinces of Dalmatia & Pannonia.It's just that Paul, if writing in the mid 1st century, would be more likely to use the name Dalmatia as opposed to Illyricum as the person writing 1 Timothy under his name did.
"Fellowsoldier" in the Pauline epistles is more likely to mean fellow preachers in hostile territories than members of the Roman army.
Damascus got outside Nabataean control in 64 BCE. So it would be a minimum interval of 20 years between Paul getting out of Damascus and him visiting Corinth (according to my study, with Paul living in 1st cent AD, that interval is only 12 years).So if Aretas III was ruler from 87-62 BCE there is no chance that Paul could be writing to the Corinthians after 44 BCE?
As I said, that minimum interval, with Paul assumed to live in the 1st cent. BCE, can be easily more than 20 years. Certainly 20, 30, 40 years (taking in account Illyricum and Achaia started to exist as Roman provinces in 27 BCE) is possible, but it is a stretch.
Cordially, Bernard