Two letters words

I am using DevonThinkPro in Hebrew script, and found that the function “Words” doesn’t list words having less than three characters. Is this a bug?

No, not a bug. See Tool > Concordance. The default is to not include words of less than 3 characters. You may cange that to 2 characters, which will somewhat increase memory requirements. Be sure to Update the Concordance after making a change.