I have added that last "On Track" result.
As for the other change, can you clarify if you feel that your original question was mis-stated or if my formula does not match the result stated in your original question.
If you need to restate your original statement, please restate the whole statement with your revision, and note that the tests will be performed in the order of your words.
IF(
[Date Field1] < Today() and not [Check Box 1], "Late",
[Date Field 2] < Today()
and
(Trim([Field1])="", or Trim([Field2])="" or Trim([field3])=""), "Late",
[Date Field 3] < Today()
and not [Check Box2]
and not [Check Box3]
and not [Check Box 4], "Late",
[Date Field 4] < Today()
and not [Check Box5]
and not [Check Box6]
and not [Check Box 7],"Late", "On Track")