We're noticing that the mailbox forwarding mechanism is not sending Chinese characters correctly. In our table we have a data type text for the data coming in from Genius Connect. Can we change the database schema from text to ntext or does that affect the app?

also our subject field is defined as nvarchar but notice strange characters . Would you be able to verify if the subjects are able to handle complex characters, please?

You can change the datatype to ntext, just don't forget to open the assign Table dialog  and re-save so GeniusConnect saves the datatype changes.

Using nvarchar for the Subject field is correct. Outlook stores the subject as Unicode, so the datatype fully supports Chinese and other complex characters. There is no limitation on the SQL side.
The reason you may see “strange” or unexpected characters in some subjects is that Outlook does not always provide the subject in a clean, fully decoded Unicode form. Depending on how the message was created, Outlook may expose the subject using different internal encodings (e.g., MIME encoded words, partial UTF 8 sequences, or legacy code pages). In some cases Outlook also returns the subject already MIME encoded instead of the final decoded text. This is a known Outlook behavior and not related to the database datatype.