I had a discussion with the developer and he mentioned that since magnitude of velocity is a quantity derived from components, it would be a redundant input in the csv. So for inputting fluid velocity, the csv is expected to have a column for time and the next column is read as x component and NOT the magnitude.
Keeping this in mind, I tried to import the following CSV and the result I got is as expected;
It can be seen that the magnitude is auto calculated from the components, as shown at T=0.0 sec.
Please let me know if you have any further query.