Hi @sns
1.You could check the viki pages to see whether there are some mistakes, here is an article for you to learn more about Customized Pages report:https://learn.microsoft.com/en-us/sharepointmigration/migration-assessment-scan-customized-pages
2.We could migrate all content type, the following article details the settings available in SPMT:https://learn.microsoft.com/en-us/sharepointmigration/spmt-settings
3.Please check whether these web parts require compiled code, if so, they are not allowed to be migrated.
4.You could check your license for InfoPath Forms Services on server or online by:
https://www.c-sharpcorner.com/article/configure-infopath-forms-services-in-sharepoint-2013-central-administration/
https://social.msdn.microsoft.com/Forums/azure/en-US/3abfb840-4bd7-47ab-b7c7-a1dc6bd79b3d/sorry-you-dont-have-a-license-to-use-infopath-forms-services-please-contact-your-help-desk?forum=sharepointcustomization
5.NonDefaultMasterPages-detail.csv contains all the sites that have a custom master page applied, you could refer to this article:
https://learn.microsoft.com/en-us/sharepointmigration/migration-assessment-scan-master-pages#scan-result-reports
Note: Microsoft is providing this information as a convenience to you. The sites are not controlled by Microsoft. Microsoft cannot make any representations regarding the quality, safety, or suitability of any software or information found there. Please make sure that you completely understand the risk before retrieving any suggestions from the above link.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.