when I insert a template into an existing card, it is always inserted into the card at the top left. But if there is already a card there, the template will be inserted on or under this card. I would expect the new card to be inserted in a free space so that I don't have to rearrange all cards. If there is no space, the superordinate card should either be enlarged or its content scaled down so that the template can appear in a free space. Alternatively, you should be able to select a position before inserting the template.
The currently planned behavior is that after clicking insert, you have the template-card hanging on your mouse-cursor, so you can choose a position and place it there.
Do you think that would be a good solution for you?