Not enough information for me to understand what you’re doing.
For extremely complex things I generally look beyond ACF and just create my own custom fields. This is easier if I do not need to actually allow the content of the field to be edited in the admin by anyone. For example, just storing my own array under a single field or a single option. This means I simply call update_post_meta() or update_option() or wherever I need to store it and let WP serialize it into the database.
If I need to allow someone to edit this in the admin I would build a repeater, yes, but I would add an acf/load_value filter on that repeater and populate the rows from my array that I have stored somewhere else. Then I would build an acf/save_post filter that would take the repeater and put it into my array that array and save it. This means that the WP admin for editing would be extremely slow but that other operations are faster. So the biggest question for me would be, does this content need to be editable in the WP admin?
