To make mods that add new buildings compatible with Trade Goods, follow the steps below:

1) Go to C:\Program Files (x86)\Steam\steamapps\workshop\content\1158310 (or your corresponding folder where the CK3 installation is located and the mods are downloaded)

2) Locate the mod you want to make compatible. To do this, you can open the various folders and read the "descriptor" file with Notepad to find the name and identify the right mod.

NOTE: I recommend downloading a program such as Notepad++ for better management and editing of these files.

3) Than go to common\holdings and open the file present here, find the line containing "castle_holding = {" and "tribal_holding = {" and copy the following text immediately after the line with "buildings = {":

resources_market_01
resources_market_02
resources_market_03
resources_market_04
resources_market_05
resources_market_06
resources_market_07
resources_market_08
resources_market_09
resources_market_10
resources_market_11
resources_market_12
resources_market_13
resources_market_14
resources_market_15
resources_market_16
resources_market_17
resources_market_18
resources_market_19
resources_market_20
resources_market_21

resources_textile #(NOTE: this not for tribal_holding)

NOTE: if only "castle_holding" or "tribal_holding" is present, perform the above operation for that one only

4) You should have something like this:

castle_holding = {
primary_building = castle_01
buildings = {
resources_market_01
resources_market_02
resources_market_03
.....
.....

5) Now copy the entire contents of this file and go to
C:\Program Files (x86)\Steam\steamapps\workshop\content\1158310\ 2689783403\common\holdings
Open the file "00_holdings" and overwrite all.

NOTE: again, if only "castle_holding" or "tribal_holding" was present before, overwrite only the corresponding in this second file.

6) Finally, open the file "trade_center_holdings", in C:\Program Files (x86)\Steam\steamapps\workshop\content\1158310\ 2689783403\common\holdings and copy, after the line containing "resources_market_16", all the new buildings inserted by the mod of interest, which can be found in the file mentioned in point 3 (if you don't know which buildings they are, you can compare this file with "trade_center_holdings" and copy the ones that are not in the latter)

7) If you make any mistakes, you can unsubscribe and subscribe again to restore the mods to their original state.