The WBTS' fundamental objection is that the Charity Commission wants to change how they do their internal policies, which they say interferes with their religious rights under Articles 9 and 11 of the European Convention of Human Rights. So expect them to push things to the European court now, if they can get its attention.
Happily, Article 9 clearly sets out the limitations on religious freedoms too - and I think the right of children not to be abused because of Brooklyn's willfully negligent safeguarding policies will be too strong a case for them to argue against. Section 2 of Article 9 clearly places the Charity Commission's actions within the law, as the British legal system has agreed.
Losing charitable status is a long way away. Could happen, but the WBTS will have to really, really try to force it to happen. There's a whole lot of other sanctions which the Charity Commission will look to first. One of the funniest is that they can, if they choose, put their own trustees in charge of a charity and have them write an adequate child safeguarding policy to send out to congregations under the Bethel corporate heading. Oh the great tribulation... we're being persecuted... they've made us have a policy which helps protect children and vulnerable adults from abusers...