Any record of a "扌笨" character anywhere?
As a native speaker of sichuanese,  I strongly suspect there is or has been such a character. Obviously this character follows the rule of 形声 and I believe it's coined by the editors or researchers. In my ordinary life, I also pronounce that sound when I express these meanings and speak in Sichuanese, but when it comes to writing, I use other "standard" characters. For example, 拌 for the first and 挣 for the second.

Also, maybe the correct character is 拌 and the standard pronunciation is changed to ben4 in Sichuanese. For example, in Sichuanese, we say dia1, meaning to hold something vertically or to lift something. The pronunciation dia 1 even doesn't exist in standard Chinese. Wikipedia shows the correct character is 提.  I'm not a linguist, but this could happen to ben 4 as well.