Say if there is cBRL / USDT pair on a CEX, we will have 2 alternate paths to go from cBRL ↔ BRL
#1: cBRL ← (on CEX) → USD* ← (on CEX or on FX platform) → BRL
#2: cBRL ← (on Mento) → CELO ← (on CEX) → USD* ↔ BRL
Having two separate paths increases liquidity and should keep peg more stable within 5 minute time periods.
Expecting to get deep liquidity on BRL/CELO pair seems pretty unlikely, since price will be volatile and it is too high risk for not enough reward for market makers.
On the other hand, cBRL / USD* pair would be more like FX pair with pretty small volatility overall so not a lot of risk for market makers to maintain decent liquidity depths. And there already is already a lot of liquidity for USD/BRL on FX markets so it is possible to hook up all those to go from cBRL → USD* → BRL with decent liquidity depth.