As I read it, and taking into account the clarification I gave in the above comment, incrementally testing a translator consists in running more and more complex programs through it, up to the order of complexity (number of instructions?) of the target program (translation of which was the goal of writing the translator), probably experimentally checking whether the translated program does the same thing as the original one. My remark was that testing the translator on only (very) small test cases is enough to guarantee it running correctly on the first try on the huge program (if one wishes to take this road, and so tests on small-scale more systematically than is usual).
As I read it, and taking into account the clarification I gave in the above comment, incrementally testing a translator consists in running more and more complex programs through it, up to the order of complexity (number of instructions?) of the target program (translation of which was the goal of writing the translator), probably experimentally checking whether the translated program does the same thing as the original one. My remark was that testing the translator on only (very) small test cases is enough to guarantee it running correctly on the first try on the huge program (if one wishes to take this road, and so tests on small-scale more systematically than is usual).