There are several potential problems that can arise when attempting to do a bidirectional sync between Excel and Google Sheets, including:

Compatibility issues: Excel and Google Sheets use different file formats, and there may be compatibility issues when attempting to transfer data between the two. This can result in data loss or corruption, and may require additional steps to ensure that the data is properly converted.

Conflicting data: When syncing data between two sources, there is a risk of conflicting data if both sources are updated at the same time. For example, if two people are working on the same spreadsheet and make changes at the same time, it may be difficult to reconcile the changes and determine which version of the data should be used.

Data loss: In case of a connectivity issue, data loss may occur.

Complexity: The process of bidirectional syncing can be complex, especially if the data is very large or if there are many different sheets or tables involved. This can make it difficult to set up and maintain the sync, and may require a significant amount of time and resources.

Security: If the data contains sensitive information, it is important to ensure that it is properly protected during the sync process. This may require additional steps to secure the data, such as encryption or access controls.

Automation: There are third-party tools available that can automate the bidirectional syncing process, but they may have limitations and may not support all the functionalities of Excel and Google Sheets.

To avoid these problems, it is important to thoroughly test the sync process and to have a plan in place for dealing with any issues that may arise. It is also recommended to use a robust and well-tested solution, and to consider the complexity and security requirements of the data before proceeding with the bidirectional sync.