According to the update at https://www.whonix.org/wiki/I2p
Accessing i2p's webinterface on 127.0.0.1 using Tor Browser is no longer possible due to a change in Tor Browser by The Tor Project. You could set to transparent torification, but then you would be vulnerable fingerprinting issues. See ticket for more.
and to what I just tried, the config page can't be accessed anymore.
Is setting to transparent torification the only option, and what does it mean? How do we do it?
Once it's configured can we turn it back?