Hi, the playtime string actually comes from RPG Maker instead of my plugin. However, from what I can see, it handles hours above 99 by default when I manually set my playtime really high: 
If this is not the case for you, you may have some other plugin limiting it to 99 hours, but I do not think it is coming from [CGMZ] as this is my test project with all 100+ [CGMZ] plugins enabled.