* Account Engagement(旧Pardot) 日本 *

So you can't have anyone continue onward in an engagement studio if you are removing them from the list that places them in the program to begin with. When someone is removed from the "starter" list it removes them from the program.  The fact that you got 10 to the next step is just an artifact of processing speed, it should have been zero. If the idea is that this branch of the program is removing them from this ES program and placing them in a new one via a different list, then put them in the new list first, and then use the remove from list step second.  Bear in mind that removing from the list that starts the program is effectively ending the program for these people. 

First comment is forget about using opens for anything. It's not reliable anymore due to the changes in mail services and apple privacy.   So all you want to track is clicks.  A click is a trigger node (green hexagon), and you can trigger to watch for clicks in a specific email.  So it has to be used after the given email was sent, where the trigger is "did this email get any clicks (or a specific link click) within this timeframe (wait 2 days or up to 2 days)."  So in your case I would put the watch for clicks trigger for email 1 directly after email 1 is sent, with a wait for exactly 2 days to see if there are any clicks, and after that send email 2. What that does is if any clicks happen on email 1 within 2 days, the campaign status does not change until the full 2 days has elapsed and the second mail is sent.  Then you put a trigger to watch for clicks on email 2 for 4 days before sending email 3 and after that you can watch for clicks on email 3 (that one you could use an 'up to' if you don't care about a specific wait time until the next step. 

Custom redirects also have completion actions, both are subject to the requirement that the browser is cookied for completion actions to fire.   I was thinking about this further, also in light of this behavior for page actions:  "Points assessed for each page with your tracking code viewed in a visitor session. If you use page actions to customize point values, only the page action score adjustment is applied. " So if you use the page score option on a page action, it overrides whatever the model says to score it. So you could say the page score is zero and only apply a score on the first visit via the tag-- if they don't have this tag, then score 1 point and add the tag. (you would not need the deduction action in that case).  But that ONLY works if they are cookied. If not, the page scores nothing.  The custom redirects does not have this option, so what I'm thinking is that you add a + score to the tag and a - when they do have the tag.  Again, my concern is the order of operations on the completion actions is not predictable.  At least if the adding tag action adds score the worst you would get is twice the score on a the first action (if cookied).   But all this is affected by what you set up your scoring model for on a page view and a custom redirect.  You can set them as zero and then only score the pages you really care about.   

Unfortunately there's no "easy" solution here. I assume what you want to do is when someone books a meeting in MS Bookings you stop further emails or something like that.  The issue is that MS Bookings has no external actions available when a meeting is booked (the fact that there is no Zapier app for MS Bookings is telling).  What I've done in the past (with someone who knows the MS suite better than I do) is we sent the Salesforce record ID to the booking page as a hidden field in the url using {{Recipient.ID}}, captured that field with the booking and then used Power Automate to pass the information back to Salesforce (we created a task on the lead/contact with an extra field that said it came from bookings), and then created a flow that watched for a new task with that hidden field, and then we used Sercante's Flow Actions for Pardot to signal back to Account Engagement that a booking was made (we used a form handler and had the engagement studio watch for the form handler to trigger).   So it's far from easy or straightforward, but it can be done.  But it only works if your records are in Salesforce.