Hey bud. Your site says you want feedback. Here is some feedback:
If you want someone to try your pack, get the invisible pig that you cannot see or hit out of the game so they don't die on day one and can't go back to pick up their grave cause the invisible pig keeps attacking them. That way, if they can play it for at least one minecraft day, maybe they will like the pack and want to continue playing it. And btw, particles set to "All" in the setting, the invisible pig emits no particles of any kind, like infernal invisible mobs would. So I tried the pack for about 8 minecraft hours If this ever changes, please give me a shout, I would love to give it another go.
It is possible you have found a small bug. Invisible pigs are not a built in feature of the pack. This sometimes occurs though and with modded Minecraft sometimes things happen. When this has happened to me and has, even while casting, I have logged out and back in, and then I can then see the mob. When you log out and back in the hit box is visible and the mob should be visible and able to be killed.
Although this happens, it is very very rare occurrence and something that is on the list of open issues.
We are making small changes and updates as the mods are updated / fixed. Please keep in mind, we have no intention of making the pack unfair.
We have over 20 mods with updates for the next update, and a few config changes. Hopefully you will give the pack a try again. We should have an update for the pack sometime this week.