Hmm...here's an idea.
Say the Spanish come across the balloon-users and although some of the more degraded, fanatical conquistadors view them as demonic, they're restrained by the smarter conquistadors and/or the priests.
They then bring some of the Indian techies and balloons back to Europe.
Could the Spanish put them to good use and how long would it be until the other European powers develop them?
The Spanish could use balloons as experimental recon devices in the Italian or Dutch wars of the 16th century the way the revolutionary French used balloons in the 1790s.