I can't really give any suggestions about the warm starting. I would imagine that any combination of imperfect injectors, injection pump, pump timing, batteries, starter, etc would progressively cause harder starting, and adding fuel and/or timing might help in some cases. I would think that it would be safe to add 10-20% fuel to that table in the temp ranges you are targeting and see what happens.

I will try to find some time in the near future to look at the code that deals with starting and work to expand the tables/scalars and documentation for them. Maybe then I can give some better suggestions, but keep in mind I'm not an experienced diesel tuner.