I am not certain what you want from this forum, but there is no possible way anyone here can provide you with a definitive answer without seeing any documentation.
If you are seriously in doubt, you need to consult with local legal counsel who can review the case. As a beneficiary of the trust, you are entitled to an accounting.
On a cursory glance, the amount of tax your brother paid on the amount of gain (long-term) stated sounds rather high. Had he filed a 1041, the tax on that capital gain (assuming no other income) would have been much lower.
Again, and no offense intended, if you want a definitive answer, you will have to contact a local tax or legal professional who can review the relevant documents and, frankly, you will not be able to get any kind of definitive and authoritative answer by repeatedly posting on this board.
