Code:
perl -pe 's/^$/%%/sg' < djvu1txt.txt | perl -pe 's/\n/ /sg' | perl -pe 's/%%/\n/sg' | perl -pe "s:^ +::" | perl -pe "s:^([^[]+?) *(?=\[):\1\t:" > new.tsv
But again, the text quality is low and it requires manual correction to obtain useful results.