pxExtractDataWithArgs should be present in Pega-BIX:07-10-17 version. Are you using the version of BIX which is part of "additional products" of the distribution image of Pega 7.1.9? If yes, then the highest version of Pega-BIX should be 07-10-19.
Then you using BIX from Pega 7.1.5 and not from Pega 7.1.9. Please check the additional products folder of the Pega 7.1.9 distribution image to get the version of BIX compatible with Pega 7.1.9. Import the rules and you should be able to find pxExtractDataWithArgs activity.
pxExtractDataWithArgs activity does not need pyWorkPage.
Did you get a change to look into the "additional products" directory of your 7.1.9 Pega platform distribution image? It should contain the BIX package which is relevant for 7.1.9 and that once imported should get you pxExtractDataWithArgs activity.