We are migrating a Magento2 site to Magento1 What would be the best way to get customer and order data over from Magento2 to Magento1? Should we build an API bridge or are the database tables similar enough that we can just do a dump and import?
You should try ubertheme tool for data migration from Magento 1 to Magento 2. here's the link for this tool.
Below link will also help you if you have any confusion in above link.
You shouldn't use Magento 1. If you don't want to use Magento 2, You should move to another platform. Because Magento 1 is ending for a long time ago. It means your website will don't get any updated security. A lot of Magento 1 website got an attack that way. Some week ago, one of our customer got attack(they use Magento 1), they lost all data.