While it is true that on Arena the Burmese can be quite a strong play - they are very 1 dimensional on that map (very similar to the Goths in that regard). If their one strat doesn’t work - they are often in a losing position. A “glass cannon” as BomberGriffin stated.
As soon as you see certain civs, you know the strat the opposing playing is going to follow, and you can adjust your strategy accordingly.
Arambai are hard countered by skirms & castles.
That being said, I do agree that it seems ridiculous to have a UU that is a ranged mounted battering ram…
I normally am not a proponent of “nerfing” units, but the Arambai was an addition to the game that I believe has been broken since its inception. I definitely believe that its attack against buildings needs to be lowered significantly.
Overall though, the counter is straightforward, just annoying to deal with.
This also has been discussed in some detail here as well for some further reading 