cantoresq: I like the thought that you mention, and the idea of trying to build unity out of any event, but I don’t think that is the purpose of this Bracha. We are recognizing that what the rest of the world thinks of as tevva (nature) is in fact nothing other than Hashem running the world. That the sun lines up in the way that it does because Hashem continuously makes it do that. Moreso, this bracha is said on no observable phenomena, so it can only be thought of as a complete recognition of the absence of tevva without Hashem.
As far as the accuracy of the calculation goes, we find that for matters of Halacha calculated by the general populace, approximations are preferrable to exactness. For calculations done by a Bais Din, such as aligning the Hebrew lunar calendar with the solar year, we use a more exact calculation (based on Rav Ada bar Ahava and not Shmuel, we have a 19 year cycle that includes 7 leap months). For other calculations, such as when to begin saying v’sain tal u’mattar we use Shmuel’s calculation (60 days after t’kufas Tishrei, which is not 60 days after the true equinox that happens in September).
ames: I think you should ignore yossiea, a poster from whom we never hear anything but venom. Let him vent on another site; or on this one, to deaf ears.