Upon healing, it's stated that "Bandaged/Disinfected wounds on your [body part] _was_ healed", as opposed to "_were_ healed".
For it to be phrased as "Bandaged/Disinfected wounds on your [body part] _were_ healed", as the plural "wounds" is what the verb "was" is referring to.

I am inclined to remove the word "was" entirely, as the word "healed" alone is sufficient:
"Bandaged wounds on your torso healed."
"Disinfected wounds on your arm healed."
To my eye, this phrasing gives a better sense that the wounds just now healed as the message was printed.
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I am inclined to remove the word "was" entirely, as the word "healed" alone is sufficient:
"Bandaged wounds on your torso healed."
"Disinfected wounds on your arm healed."
To my eye, this phrasing gives a better sense that the wounds just now healed as the message was printed.