Only the Bengalis attacked Nepal and they won looted temples and then went back, the British attacked Nepal over territory issues and in the treaty they got all the territories they wanted. They never bothered to conquer Nepal because they knew the terrain was not worth sending men into and then having to face insurrection. Mughals never bothered to attack Nepal because their was never loot worthy of such a campaign.
Shah Jahan never ordered a military campaign on the Ahom, there were border skirmishes but never outright war, when Shah Jahan got sick the Ahom attacked up to Decca and that is why after Aurangzeb came to power he wanted to teach them a lesson and he mounted I think three campaigns against them. Like I said he was a zealot so he always invaded everything.