Current problem in ArchiCAD - title blocks should be placed on Master Layouts. If company has many different title blocks (various sizes, designs, purposes) - it can have dozens of Master Layouts - sometimes up to 20. If use title block as GDL object with access to it's settings via Layout Settings - it can give more flexibility to title block itself (having one object with various parameters) and save amounts of Master Layouts.
I get what you are trying to do, but then you are trying to modify the title block object on a master (through the layout) and not have the other layouts using the same master update as well.
I think this would get very messy.
So either have multiple masters with the different title blocks, of just place the title block on the layout it self.
There is nothing to say the title block has to be on the master - other than that it is convenient to update it in one place and have all layouts using that master update as well.
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