I’ve noticed an issue with using MUDFISH alongside FFXIV; when using the ACT parser to parse damage numbers, the numbers turn out all wrong and inflated. This doesn’t happen when I load into FFXIV without MUDFISH or when I play FFXIV using WTFast, confirming that this is an issue with MUDFISH itself. Is there anyway around this?
Frankly speaking I have no idea what ACT parser works internally. However you can try to test with one of followings to check what Mudfish’s feature could cause this problem:
* Play it without Full VPN mode + without FastConnect mode. It means just with item equipped.
* Play it with Full VPN mode + without FastConnect mode.
I’d created a wiki Final Fantasy XIV - A Realm Reborn for this purpose. 
Thank you for your information.
And I’d created a ticket for internal purpose to track this issue too. If there are any news regarding to this issue, I’ll let you know.