About your reply to #3: You said the market went up and closed on the line. Well, that is what you might see with your eyes, but the EA considers detailed values. You might know this already, but just making sure. For example, if the line is 1.50105 and the market price only went up to 1.50104 then it might look to you that the market closed on the line, but in reality the EA would consider the market still below the line. Even in the image, it looks like the value was below the line if you look closely. Then you said the next candle closed below the line. I do not see this. I see the next candle's black line clearly above the red line. So we have a black line that was below the red line and then it went above the red line the next candle. It seems the only new piece of information here that was not stated before is the direction of the black line. So it cannot simply cross as you said before, but the actual slope of the black line needs checked too.
About your reply to #5: I'm not sure what you mean, but the EA doesn't care what is visible to a human eye. It considers data such as if a value is present on a certain candle location or not. So it would see a value for a blue line at a certain candle location regardless as to whether or not you see it on the chart. The zoom level or window size or anything else hiding the blue line would not matter. I think the answer to my question is, yes, the EA would have to ignore the opposite direction line in this case.
Let me know your thoughts. It's becoming clearer:D