Just checking we played this right. At the end of turn 8 after getting income for trade goods the player used the trading house building to trade in all their trade goods they had 15 in all which gave them $75 also because they had the wealth card 1vp for $5 gave them 15 points also at end of game scoring they received the victory points for the amount of dollars their trade goods generated during phase 3 of turn 8 Is that correct Thanks
Yes, that is correct. The Trading House is used during capital buildings benefits phase which is after income so they score as you outlined above. (Or more since the money also scores independently of wealth as well, a weird quirk of the wealth tile).
I have noticed in the games I have played that Wealth can be a huge points swing when combined with other economic powers and I will often be 'forced' to make a play for Wealth to prevent a specific player from getting it and securing a victory in a manner similar to what you described.