Lower lid fat
At 1 1/2 weeks after surgery, you may still have swelling of the lower lid which will resolve time but could take several months. A repeat steroid injection in a few more weeks may help as well. Another option you could discuss with your doctor would be 5 flurouracil (5FU) injections of the fat. This is an off label use of 5FU but it is known to help soften and flatten inflamed tissue and scars.
Swelling post fat injection
This can occur when you inject fat to the lower lids and since it's only a week and a half give it some time.Maybe a little lipo with local or a small incision and excise it.
Do I need this surgically removed or will it go away?
I think at this early post op period I would just observe the area and see what happened. It is likely to settle down on its own.
Will most likely resolve
Definitely would wait it out. May be as long as 2 months before you know. It can be removed without going under anesthesia if need be. If it was symmetric immediately after surgery and developed a few hours laterm, it is probably due to swelling rather than uneven fat placement.
A lump after lower lid fat grafting, would it go away?
Thanks for sharing your photos. It is early to tell if its only been a week and a half. I suggest watchful waiting as some of this could be blood and inflammation and may come down in size with time. Make sure to continue to follow up with your plastic surgeon to monitor the progress of this lump. It is possible that surgical removal may be needed but I won't rush into another surgical intervention now. I doubt that this lump from its current locations is causing any pressure on your eyeball.