Is the aforementioned Hadith, which describes God's wisdom in creating certain human organs and their characteristics, authentic?

The aforementioned Hadith is very weak when attributed to the Prophet, peace and blessings be upon him. At best, it is a statement by Ja'far ibn Muhammad. The weakness of a Hadith is recognized by examining its chains of transmission (isnads), its defects ('ilal), and its narrators (rijal), not merely by conjecture. As for a Hadith contradicting a scientific fact, this requires deliberation, as the fact might not yet be definitively established, or the Hadith might not address that scientific issue at all.