Fiscal Year change in Production from K4 to V3 in Rise with SAP Public Cloud

Dear Expert

One of my client using Rise with SAP Public cloud.

Due to some other reason, they have maintained incorrect K4 Fiscal year variant in Production, now they want to change to V3.

What are the difficulties are there by changing this Fiscal year change from K4 to V3.

We need to know the impact of doing this changes and is it suggestable to do such changes?

Note: already they gone Golive having this incorrect setup.

Regards

Saravanan