Lilian is a tricky character, perhaps not the best mother and stepmother, and what seems to be a very headstrong personality as well. But considering she told Leopold "kings marry princesses", knew she was marrying a man whose first wife would be forever young, beautiful and universally adored (yikes), and gained almost nothing in return but scorn, a permanently terrible reputation, and being imprisoned, starved, and nearly murdered by the Nazis... I can't think she was out for much.
And ever since I learned:
-She insisted on getting proper medical attention for Albert in captivity and likely saved a future king's leg from gangrene
-And she was smart enough not to give her family the "vitamins" which, when analyzed, turned out to be cyanide pills...
Lilian has been okay in my book. Major errors of her own, too, but she probably does deserve a more evenhanded appraisal of her reputation... which is difficult when she basically lived as a private citizen and when seemingly nothing will change her Belgian image.