Many people never flew a reversal in their flying career
True! And you don't have to do it. But should you decide to do it for whatever reason then it's not a big deal. Engine fire at take off teaches you to do ECAM and fire goes out on first or second agent discharge. When it doesn't it's all yours. If it works no questions asked. If it doesn't then with or without you conclusions will be drawn. I know one case where with failure not fire radar vector was asked for and given and yet the pilot overshot and went round.