I know, it's just... there's not much we have to go on. Given Garlemald was evidently a "fledgling" nation before Solus' rise to power, there may not be much behind it. That said, if there are any Garleans left who remember the Republic, they'd have to be quite old - Solus took over as Emperor approximately fifty years ago and was approximately 80 during 1.x. Anyone able to remember the Republic would have to be that old or older... and in this fantasy world where people don't have the greatest life expectancy, combined with Garlemald's warlike nature following zos Galvus' crowning, the likelihood of there being many such people is rather low.
Still! There are always people who disagree with the warlike path many such nations choose (Cessair of Mhach, for instance), so even if there aren't any Garleans who really remember the Republic if we go to Garlemald we might find an ally who isn't an expatriate. Maybe. Possibly.
Ehh... more like Rome, if you ask me. Solus zos Galvus' rise to power has many parallels with Julius Caesar (with some Gestahl thrown in for good measure), and the Garleans frequently use Latin names and phrases.