MacOS Catalina is 64-bit only. It is also still in Beta so using Catalina before release will without a doubt create issues.

This said FF XIV runs via Cross Over which in short is an over-glorified WINE setup. Currently People are having issues using WINE itself on Catalina.

IDK if link posting is allowed but a quick google search will shed some light on the matter.

The current system Reqs are: macOS Mojave 10.14.3

So my suggestion is revert back to 10.14.6 and wait for 10.15 to be officially supported if possible.

I was hoping the Devs would reply on the matter further but I figured since its been about a week I would chime in.