The phrase 'mainly revolves around' is correct and usable in written English.
You can use it when discussing how something is influenced or structured by a central point or idea. For example: "The theme of this novel mainly revolves around the concept of sacrifice."
That mainly revolves around whatever technology is available.
The story mainly revolves around an aristocratic aunt and her youngest niece and their submissive reaction to economic and social changes.
The transformation of the correlation patterns of the regional consumer markets mainly revolves around three core correlation modes and each transformation needs to undergo 4 non-core modes.
The transformation of the interaction patterns mainly revolves around three core interaction modes and each transformation needs to undergo 5 non-core modes.
Although it is being described as "gripping" and "redemptive", Alone in Berlin is a rambling story that mainly revolves around the unappealing inhabitants of a single apartment building.
Tuesday mainly revolves around the fact that none of you can believe it's only Tuesday and then, before you know it, it's Wednesday again.
Abba to Zappa's guest columnist James Blunt reveals how he enjoyed some apres ski in Switzerland over Christmas and New Year - 'it mainly revolved around drinking beer.
The après-ski side of it has moved on from the Eighties cliche of Swiss fondues; for me, it mainly revolved around drinking beer.
During this period, defences in Australia mainly revolved around static defence by combined infantry and artillery, based on garrisoned coastal forts.
The three of them shared several, mainly revolving around surprising gestures or acts of kindness.
To date the discussion has mainly revolved around the trade-off between privacy and security.
