My answer is reaction to both the previous answer as well as accounting for @DoubleAA's comment.
I've had this situation a few times in my shul while I was reading the parsha. Our shul rarely has kids attending. (Sad, somewhat...) When I fiind a questionable mistake, I call the rav. He makes the final decision. Sometimes he can tell, it's definitely no good - it looks like a yod when it should be a vav, for example. To make this decision, he compares what he decided with a similar letter in a completely different pasuk. (Caveat to this, which I'll mention, below.) If he's not sure, he will let the reading continue, but, that Torah will not be used the following week until a Sofer can correct it.
Caveat - A number of our Sifrei Torah have been significantly repaired and parts of been corrected and pieced together by multiple Sofrim. (Talk abot a challenge for me as a Ba'al Kri'ah!!!) So, when the Rav does a comparison with another pasuk, he does it somewhat quickly, to avoid tircha d'tzibbur. If there's a section where the style suddenly changes to a different sofer's style, he tends to be a bit more lenient.
I can't state, offhand, the original source of where my Rav gets this halacha / practice from, but, he is more knowledgable in halachot than I am, and he is the rav, so I have to respect his decision unless I can justify that he is wrong! (After all, you do state in the M.Y. policy CYLOR!)