I found error on the page: https://opennmt.net/OpenNMT-py/FAQ.html#opennmt-tokenizer
OpenNMT Tokenizer Additional options are available:
…
src_onmttok_kwargs: additional kwargs for pyonmttok Tokenizer class, source side;
src_onmttok_kwargs: additional kwargs for pyonmttok Tokenizer class, target side.
maybe there should be tgt_onmttok_kwargs