Screen stage-scrolling at a constant rate? (.gif included)

I'm trying to make screen transitions reminiscent of older Nes games like Mega Man.

When the player gets to the edge of the screen, they layout shifts to the next one.

Right now, this is what I have. My issue is: While the screen is transitioning, the closer the camera gets to finishing the transition, the scrolling speed begins to slow down. This makes a nice smooth effect, but it's not what I'm going for. It needs to be a constant speed all the way into the end of it.

(Linking this because the gif image is huge)

i.imgur.com/ug0aoCc.gif

And here is the event sheet:

Additionally, how would you suggest I trigger disabling the Player movement and "slide" them into the new frame like in the old games instead of giving them free control during the whole transition? This part was giving me trouble as well.

That's what lerp does - if you want steady movement you gotta do something like if x < targetx do x = x+dt*400

Or possibly just use a moveto behaviour on a scroll helper object