The taxation paradox has a dimension beyond the simple mechanism problem. Even if you accepted that funding reparations from general taxation was appropriate, the British Caribbean community would be contributing to those payments without any consent having been sought or any opt-out being offered.
No British government has asked British Caribbean people whether they want their taxes used this way. The CARICOM campaign has not sought the endorsement of the British Caribbean community before claiming to act in their name. The Caribbean governments making the demand were not elected by British Caribbean people and are not accountable to them.
This matters because the reparations campaign frames itself as acting for the benefit of Caribbean-heritage people everywhere. But the specific mechanism proposed, taxation-funded payment to Caribbean governments, was designed without any consultation with the people it is meant to help and would operate without their consent. The people whose interests are supposedly being served have no say in whether the mechanism is used, how the money is spent, or whether the outcome actually benefits them.
A campaign that genuinely prioritised the interests of Caribbean-heritage people would have sought their views before designing a mechanism that uses their money. The fact that it did not suggests that the campaign is more focused on the political relationship between Caribbean governments and Britain than on the welfare of ordinary people of Caribbean heritage.