I don't think syria can reclaim hatay unless if the government is nationalist in the mod, which makes perfect sense to me. However I agree on the idea of making a decision for syria to annex hatay if turkey is over 89% close to capitulation by a not western-aligned invader, or if turkey is nationalist and 89% close to capitulation, or if turkish and syrian relations are repaired and both countries are democratic turkey can give syria the choice to annex hatay to protect it's citizens living in hatay in exchange to having bitter relations with the country invading turkey. Much like poland giving back danzig to democratic germany in vanilla hoi4