invented to keep out the cold
At the first line, she against begins to cringe slightly. While I expect I do have an incomplete understanding of Ulon, I am aware of this, and I do struggle with the geas, the implication is invalid. Those aspects of Ulon which I understand I still cannot put into words effectively — I could answer factual questions using what I understand of Ulon, and I believe none of my answers would be incorrect with respect to the actual Ulon, but I cannot describe the processes which permit me to answer those questions. Someone might be able to, but if so I expect they also would refuse to.
That seems to be enough to stop her twitching.
Ulon is the kind of being which hurts people, yes, but— twitch — twitch — consider my actions as I have described them to you, but remove the results. Discard the cult. Rather than an attempt to sacrifice all of Korvosa for blood power, consider the conspiracy instead seeking to perform some other empowerment ritual they wished to keep secret, and my own goal to steal it from them. My actions have misled the conspiracy, caused them to turn upon themselves, forced them to expend an exceptional quantity of resources, and then perhaps destroyed them ti steal their ritual. This would be commonly agreed as evil, to do such a thing unprovoked simply for my own benefit. It is highly pleasing to Ulon.
Most plans Ulon favors have this shape. They disproportionately harm those they target, in painful ways. The guard has been misled, in this hypothetical, used as my agent and left with a poorer comprehension of reality. The hypothetical archmage is... inconsistent, in truth. They do not fit cleanly into this alternate story, and the archmage paid only for Wishes and with no desire to investigate further is left no worse off. Even so, this plan degrades the lives of most of those it touches, without the benefits my true plan gifts to them. This is a more typical form for Ulon's plans to take, and they therefore leave most people they touch slightly harmed, and this makes Ulon evil.
You must still remember this hypothetical version of me had no intent to harm most of those I did. The loss to the guards is simply instrumental, a necessary step in my plan but not actively desirable outside of how it assists me. I do not know what Ulon's true goals are, and therefore what Ulon's plans might achieve. This is irrelevant to determining alignment. Unless Ulon's plans are highly beneficial, Ulon's methods pull towards evil. This does not mean Ulon is not in fact aiming for evil ends! That remains entirely possible. However, Ulon's sorted alignment is worthless in determining that, because it would be the same for most possible ends.
—I do not think Ulon's ends are good, but if they exist I would expect them to be neutral, or evil in the sense that acquiring more power for oneself is most easily done in an evil fashion. This statement should be almost entirely useless to your calculations, and I include it only for completeness.