Glad you like it
The Cool SL Viewer has been supporting TPs up to 4096m since day one after the release of Havoc4... Not sure what is this bug you are referring to, but I never saw it happening myself. As for the patch on the JIRA, it looks like an ugly hack (truncating the value of a variable instead of looking into why its value could eventually get too large)...
I do not think of this "feature" as an improvement... For a start, even if the
display of the build tool floater is limited to three decimals, you can actually enter more decimals for each parameter (it will appear as rounded after you hit ENTER, but the value you entered will be taken into account).
Beside, too many decimals make things look only more complicated and distracting while giving a false sense of accuracy (mind you, the accuracy of the LSL trigonometric functions is quite rough, and a three decimals accuracy is not even always possible: try to make an horizontal axis (elongated cylinder) rotate without precession in any other alignment than North/South or West/East for example, and you will be surprised...).
Finally, the best practice when building (and to obtain well aligned prims and builds) is precisely to do it by entering round numbers for coordinates and sizes.
If you really need more decimals, you can always edit the floater_tools.xml file since it's not a hard coded limit, but I don't think the majority of the Cool SL Viewer users would like (and even less need) to see more decimals in the build tools floater.
This involves a lot of changes and code review for a feature which is not even yet implemented or used anywhere... So, it's not worth implementing it for now. As for the maximum draw distance, it is capped at 512m (not 256 !) in the preference floaters, but you can manually set it to pretty much anything via the RenderFarClip variable.
Setting forcefully the Windlight settings of a resident's viewer is for me an hostile act... What if their video card can't handle a particular setting (bug or non-implemented OpenGL functions) ?... What if the user prefers speed to prettiness (when you crawl at 5 FPS, believe me, you don't care the least if you can't see the clouds in the sky but can gain 5 more FPS without them !) ?...
There is such a feature in RestrainedLife already (and therefore in the Cool SL Viewer), but it can be disabled by the user (I was actually the one who implemented the disabling flag and asked Marine to make it official in the RestrainedLife specs and following patches, which she did).
Like you admit yourself, the OS functions are a moving target... Beside, the keywords.ini file is not the only thing to change in the viewer to implement full support for them (it only controls the highlighting and tips in the script editor, but does not deal with script compilation, for example). I've got better things to do, so this will stay low priority on my ToDo list for now, I'm afraid.
For now, and until Linden Lab issues a policy about what is allowed or not when dealing with contents backup via third parties viewers, I'll refrain from doing more development on this type of features...
Sorry for the late reply, but your post was long and my real life busy... Enjoy the new releases I posted today and happy New Year !