What does "primarily of interest" mean?

Question

The Fed also announced a few housekeeping changes, primarily of interest to its close watchers. Fed officials are now prohibited from speaking about monetary policy for 10 days before a policy-making meeting, rather than one week. The Fed also said it would expand the information provided with its quarterly economic forecasts to include an illustration of the uncertainty surrounding the projections.

Source: https://www.nytimes.com/2017/02/22/business/economy/Federal-reserve-minutes.html?ref=business&_r=0

Answer 1

In this context:

• primarily means "mostly"
• of interest means "of concern"

Essentially, the sentence answers this question:

Changes have been made – who will be most concerned or curious about these changes? (Answer: Those who watch the Fed most closely.)

Answer 2

One could argue that the modifier primarily is misplaced in primarily of interest, and recommend this:

...of interest primarily to its close watchers ...

or

...of interest to its close watchers primarily ...

since the intended meaning is "not of much interest to those who do not watch the Fed closely", that is, of little concern to them, and of concern mainly to those who do watch the Fed closely.