There are definitely problems with the T6GLN1. RTM and custom balance sheet.  
The assets are fine, but the Liability Type O GL accounts are missing the brackets.  In the case of  retained earnings, if they are negative(a credit balance) that would normally print in liabilities without brackets(since all those brackets would be distracting), and this means that positive amounts  ( a debit balance) should print with brackets.  They seem to in other parts of the custom report, but not in the Owner's Equity part.
Bigger problem in my opinion is the fact that the total for current earnings in my custom report seems to depend on my running the standard balance sheet first.  If I run the custom statement first, the current earnings are not correct and balance sheet does not balance.  If I then run the standard balance sheet GL-F, and run the custom report again, the number is correct and it balances!
 
Of course there is still the problem of no lookup, also.