bcp error: date invalid date format
Your bcp format file has six columns defined, but the csv dataset and table have only five columns.

I was able to import your sample data successfully using the format file:

14.0
5
1       SQLBIGINT       0       8       ",\""     1     transaction_id      ""
2       SQLINT          0       4       "\",\""   2     transaction_no      ""
3       SQLINT          0       4       "\",\""   3     store_no            ""
4       SQLINT          0       4       "\",\""   4     register_no         ""
5       SQLDATETIME     0       8       "\"\r\n"  5     transaction_date    ""


This works regardless of whether the table columns are NULL or NOT NULL, though it is good practice to always specify this in your CREATE TABLE statements to avoid ambiguity.

That said, importing csv data prior to SQL Server 2017 can be difficult, or even impossible. From 2017 onward, you can use the RFC 4180 compliant:

BULK INSERT dbo.my_test
FROM 'C:\Temp\my_test.csv'
WITH (FORMAT = 'CSV');


See Using the Bulk-Load Tools in SQL Server by Erland Sommarskog for a comprehensive description of the topic, including the special problems posed by csv data.