The meanings of Hebrew verbs change considerably for the different stems
(פָּעַל
Qal
פִּעֵל
Piʿēl
הִפְעִיל
Hip̄ʿîl
נִפְעַל
Nip̄ʿal
פֻּעַל
Puʿal
הָפְעַל
Hop̄ʿal
הִתְפַּעֵל
HiṯpaʿēlVan der Merwe, C. H. J., Naudé, J. A., & Kroeze, J. H. (2017). A Biblical Hebrew Reference Grammar (Second Edition, p. 73). Bloomsbury; Bloomsbury T&T Clark: An Imprint of Bloomsbury Publishing Plc.).
It is desirable to have an uncomplicated way to have the charts graph only the usage with the Hebrew verb stem in use when charting the Hebrew verb word study because the senses of h other stems are usually irrelevant to meaning in the word generating the word study.