The other insulin options are:
Levimer - which works in the same fashion as Lantus - however, it is a different formula than lantus and some cats do better with levimer than lantus - not sure why....
Prozinc - this insulin is a little more forgiving in when and how it is dosed. Meaning that if you can't stick to a 12/12 schedule, this will allow a it more leeway than lantus or levimer.
These three insulin - lantus, levimer and prozinc are really the only ones recommended for kitties. All the others are short acting, harsher insulins and tougher to regulate with. It is possible, but it's more of a challenge and the insulin may not last the full 12 hours as the three I mentioned. Which is why we try to steer people to one of these three.
Personally, I would give this a bit more time to see if you can find the right dose for Elian before changing insulin. Knowing that you do have other options is good and you can spend this time learning about each of the insulins above so if you decide to change insulin, you know which one to choose next.