Swordsman counter to camels isn’t better than pikes, but can be a good choice.
Using longswords to counter camel by Franks and Huns are very rare. It is very hard to tech into, and longswords are food heavy, which hampers knight production.
In most cases, these civs use pikes, since they are cheaper, and can kill camels faster.
In some cases, they can also use crossbows, since Frank and Hun crossbows are quite serviceable in Castle Age (and camels have poor pierce armour). Also, crossbows are more of a power unit than longswords currently.