People really should read more.
From OLC's Ubermod changelog, on the thread's first page:
v1.6
- Tweaks and fixes to the appearance of underwater 3D objects and bitmap particles, particularly at night.
- Included Rubini's Water Stream mod in OLCE2.
- Merged the 'flat sun fix' modlet into OLCE2.
That means, the flat sun fix is already merged into OLCE2, so it's redundant to enable it again.
I have just OLCE2 with my mod and I have sun halo like the two screenshots above.