Really? I'm sure the "higher versions" could at least run fine on the "New Nintendo 3DS" which has some exclusives of games that are higher specs than the regular 3DS can handle, such as Xenoblade Chronicles, Minecraft , and Legend of Zelda: Majora's Mask.
To quote the differences between the original Nintendo 3DS and the "New Nintendo 3DS" from online:
"The New 3DS is an interesting revision of the older hardware - ARM11 core count doubles and clock-speed radically shifts upwards from 268MHz to 804MHz, while memory and VRAM increase substantially".
I don't know too much about this specifically, but based on what I've seen, I believe newer versions of Terraria could run just fine on the "New Nintendo 3DS" if it can't on the old one.