This civ is situationally strong.
The settler bonus is very, very strong. This allows for very early expansion without needing to go to war on Emperor to Deity. You can easily fill up the continent area without worrying about pressure. You can also expand later in game this way too by moving the capital and fill in a new continent area. Useful if you need to grab strategic resources like uranium, aluminum, oil, etc.
The thing about the harder difficulties is getting settlers out QUICK to get things rolling. You cannot keep one or two cities and always war the neighbor and expect to win. While fighting you have to find a way to get out more settlers or you will get outpaced by the AI big time. With Carthage, why bother? Policy card + Magnus, plus government building, and I will have the fastest 10 cities on the whole map with no warmongering at all. The AI won't be able to keep that pace with me.
The only thing that will screw this civ over would be a bad map without a coastal start or having to waste 3+ turns to get closer to the coast. The coastal bias works well most of the time.
I think this civ is powerful for multiplayer. You can expand faster (something that is very crucial in multiplayer) and you get a small science lead on turn 1. If you have a rough war you can move your capital back to another city until you can either beat them into a peace deal or push them back.
I think this is a T2 civ. T1 on an Island plates map for sure just for the loyalty and harbor bonuses.
Some of you guys are weird. This is probably the best civ I see for peaceful expansion out of all of those other "peaceful" sim-city builder types most of you guys like. Sure you could warmonger with Carthage but.... they are almost a blank civ for that. They should have given them the friggin elephant. The Steel and Thunder mod will have your war elephant Jewelrunna, don't worry about it.
I see what Eagle Pursuit is going with the potential for loyalty flipping, but.... that is not as easy to do as we think. For starters, you won't have the population pressure and you have no Entertainment Districts to run bread and circuses. You can use a upgraded Amani but... I dunno. I would need to test that out to really see if it works that well or not.