Hello Johnny Solas,
Please replace your code with the one below and give it a try:
data = [{
"role_id": 1,
"partner_id": 14,
"mail_sent_order": 1,
}]
# Create the record in sign.send.request.signer
env['sign.send.request.signer'].create(data)
Let me know if this works for you.
Thanks!