Perhaps I'm not understanding how the productivity on Interplanetary Trades is supposed to be calculated.
As far as I can tell, all the usual productivity bonuses to trades apply, except for those from the involved items considered interplanetary. If that's intended, I'm fine with that, but it's not clear.
The breakdown tooltip confuses me, because it also shows the bonus from the interplanetary item, even though that doesn't contribute to the total.

As an example on Nauvis, I have a trade for coins -> calcite. I have a trade bonus from quests of +15%, and silver star calcite for +10%, and the productivity breakdown tooltip on the trade shows both, along with a total of +15% in the tooltip and on the blue arrow. Actually doing the trade gives me 15% of the purple bar as well.

Side question: shouldn't heat pipe, heat exchangers, and steam turbines be native Nauvis items, and not considered interplanetary on Nauvis (native to Gleba)? I can understand that this happened because of Heating Tower tech, but it doesn't seem right.