Hello @Jonathas Sucupira , Thanks for using Microsoft Q&A Platform.
Document Intelligence's prebuilt models enable you to add intelligent document processing to your apps and flows without having to train and build your own models. So, you can't further train/customize them.
However, using custom model you can train the model to identify the different types of documents your application supports.
Regarding your second question, you can use the custom model feature to train the model to accurately capture the necessary information. You can provide the model with more data to improve its accuracy. The more examples you provide, the better the model will become at recognizing the necessary information.
I hope this helps.
Regards,
Vasavi