Query on changing default defect management configuration

hello,

We are configuring RTC for Defect management. We have made a few changes to the default lay-outs.
We need to be confirmed that these do not affect RTC's internal operations in any way, so that,
in future, we may have any trouble in production. Please guide us on these issues -

A) We have removed the Type and Filed Against field from the defect layout.

B) We are not configuring and using Releases tab. We have created our custom enumeration for that. We are not using categories also.

C) Under our project area, there is a main team area, and under that we have created several team area-s.
We drag and drop these team area-s to Quick Information section to add the team area members to the subscribers list.

D) Also, we are not using Tags, Planned For, Iteration, Estimate, Time Spent, Team and Project Area etc.
in the defect layout, as we do not need these fields.

E) We are not using the Links section in Links tab.

At present, the system seems to work fine as per our expectations.

I want to be confirmed that in future, modifying the default layout in the manner described above, may
not create any problem or restrict us to upgrade the system, if the need arises.

Your help is greatly appreciated. Please advise.