There always have been some mobs with much more hp in the mix at least since ToL. The Commanders and Spellslingers in PalLomen fall into this category obviously. They give more xp as well as the normal mobs. So I assume this is intended.
It's quite annoying that these have so many hit points since we need to kill them to get conquerors for Pal'Lomen task #3.
I had spawn Conquerors from any Rallosian. Though Commanders and Spellslingers seem to have a higher chance.
We did ours on the weekend at prime time, and there were no conquerors spawned, picked clean of course. So we noticed there was a pickzone active with only 1 group in it. It had 7 of them up, and as we blasted them, the other 3 respawned. It was quite a relief. Then of course the lieutenants are 2x as common so we were easily done.