There seem to be multiple issues with Lothlorien Outposts. I dont know whether some of them are bugs but most are.
Mirkwood Outpost gets constructed over a couple of seconds, I think that is at least a dozen times faster than all other outposts; it may be more expensive and take extra buildplots to get going but it doesn't appear like this is intended.
Mirkwood Outpost can hire Legolas and Thranduil at the same time, it doesn't put them in a que like with other buildings. Didn't check whether it can train heroes and soldiers at the same time but it's not a case with troop to troop queing.
Lothlorien Citadel on the outpost buildplot is called Lothlorien Fortress, this is a slightly confusing name, but the bug is with inconsistency as the built outpost is just called Citadel.
Lothlorien Citadels in castles have 4000 hp but outpost citadels have 6000, I think it would be more optimal if both would have 6k because Lothlorien's main structures are already more valuable than those of other factions (and more vulnerable than of other good ones), but the normal Citadels currently have the same hp amount as others. It is reasonable that Lothlorien outpost has 6k imo because it is upgraded with addons and destruction of them removes them all.
Lothlorien Citadel Outpost, when upgraded with forge (this or perhaps it is about having all the add-ons completed), has a fog nova hiding units, like one coming from upgrade in a normal sanctuary (but that one doesn't have a visual I'm pretty sure), if this is intentional it's not mentioned.
Lothlorien Citadel Outpost forge can research all the upgrades right after it is built while the forges in castles and camps can only do it previously having researched eco upgrades. (if it is to stay in some form and not completely changed for normal forge function, I think making the outposts level from outer economy upgrades makes sense).