When we discussed the respective bug report in the German forum, I had checked the trade speed to and from the gold exchange on zz2 and zz13. The trade speed was 30 minutes on both worlds (both with trade speed 2), although I had the captain active on zz13, but not active on zz2 at that time.
It was confirmed that the formula for trade movements to and from the gold exchange is 60 minutes (base value) / trade speed of the world (for zz2 and zz13 therefore 60 minutes/2 = 30 minutes), and that neither the captain´s trade speed boost nor event trade speed boosts did affect the actual gold exchange trade speed. It was also confirmed that this behaviour was not intended, i.e. a bug.
Since after today´s update the trade speed is still 30 minutes with the captain´s trade speed boost active, I would guess that either the issue has not yet been fixed or the captain´s speed boost has been excluded for some reason.
the formula for the trade speed to and from the gold exchange (60 minutes/trade speed) should be added to the respective Wiki article
the fact that the trade speed to and from the gold exchange will not be affected by any trade speed boosters (including the captain´s) should be added to the in-game description and the Wiki article as well
Please also note that this sentence might have been added to the decription of the power (event item), but is still missing in the description of the advantages provided by the captain. I have seen this trade speed topic coming up again and again ever since the gold exchange was introduced, and I really think some clear words in the wiki article could be helpful.
Comparing the Beta changelog 2.199 to the changelog 2.199 as published in the live markets, I wonder why the new features listed there (red capacity bar, activation of advisors in the "advantages" overview, changes in the hero training window) have never been announced on Beta, not in 2.199 nor in any other changelog: