I have been testing the Custom Attributes feature against the Contacts in our property. It appears that when the Contacts list is exported via CSV, it does not carry any of the Custom Attribute data that has been setup for the organisation to apply to Contacts (only a few basic columns of information are exported). The Tawk.to support chat team have confirmed there is currently no way to export or import custom attribute information into the Contacts.
I have tested using Tags as an alternative, however all the custom tags get grouped in the same cell/column upon export, meaning the data has to be split manually after export (and combined manually prior to import) for it to be usable, which arguably it is not. There are other threads going back years noting the issues with managing the tags, adding another layer of complication.
Without the ability to export or import this information, Tawk.to’s ability to manage more than just a handful of contacts is incredibly limited and unlikely to be usable in the real world.