Dear imem,
You are making very serious and unfounded accusations for no apparent reason other than what is rooted in your heart, mind and soul.
As to registering the word 'charity', when a name is patented with the Charities Commission it has to not be a gross misrepresentation of their aims and objectives. You can get an outline of their 'very strict' registration requirements from the Charities Commission, which also ensures money is going to its appropriate source BTW.
We have legislation to protect the money we give to charities. However, they are still under the legislative requirements of all the individual countries they work in too, so international charities probably have the most scrutinised accounts on the planet. These organisations abroad protect the names of the charities in much the same way as The Charities Commission in Britain
If you are genuinely troubled, perhaps you should contact appropriate people with your concerns. Legislation is not just there for them to protect their name against misappropriation, but also to be used by people who have concerns against a charity or organisation.
is Companies House, where you can write and ask them for the more in-depth legal reasons for protecting a name against misuse)
I do not know any Christian's who are particularly worried about giving World Vision their money. Considering it is them who are giving, I really think that if they were concerned something will have been said by now.
In Christ's love Carol T