Perhaps, try this:
Create an XPresso Tag onto the target object.
Take the Source Null you like to bake onto the Target Null, and drag it into the XPresso editor. On the output side use the Global Matrix.
Drag the Target Null into the XPresso Editor and create an input Global Matrix.
Connect both.
Now “Bake” the target Null. It should show up as the needed.
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If you have to do that often, please check out the file below:
Scene file
https://www.amazon.com/clouddrive/share/CjuJOyZLn0uxDX5gKtvKU7Wjlj3YanqHh0qh2mFFwDn?ref_=cd_ph_share_link_copy
You can open the C4D file then select the “SGM_to_TGM—>UserData” null and use the Object Manger> File> Save Object Preset. You can load it now at anytime you need it.
If you have it in your Object Manager, click on the XPresso tag, you will find then in the Attribute Manger a User Data entry: two link fields.
Drage the two Nulls you like to use into the fields.
Bake in the Timeline the target Null Object.
When done, you can just drag a new source object into it. The bake will create a copy anyway, so no need to create a new “Target Null” each time.
My best wishes for your project.