I found a weird glitch:
gotoroom(x,y) acts differently in different ways of executing internal scripting!

Consider methods A, B, and C.
Method A is this:
say(-1)
gotoroom(x,y)
Method B is this, which is not recommended to use:
say(-1)
text(1,0,0,4)
say
gotoroom(x,y)
Method C is the one mentioned in the 2nd post (or something similar...):
say(-1)
text(1,0,0,4)
say(5)
gotoroom(x,y)
endtext
endcutscene
untilbars
loadscript(stop)
Here's what happens when triggering the script with method A:

goes to position x,y and falls upwards... but his/her feet are pointing down! Before you can move a centered grey text box with either the last script triggered in a level outside the editor or a line with costumposition(center) (the last only happens and always happens if you trigger the script with method B first) appears. When he/she touches a ceiling his/her feet suddenly point upwards... and he/she can't flip! I'm sure this is a glitch!
When triggering the script with method B:

goes to position x,y, falls downwards and his/her feet are pointing down. Before you can move a centered grey text box with 4 lines of internal scripting appears. The 1st line was last line was a text command with weird values for x and y. When you can move and touch a floor, you can flip.
When triggering the script with method C:

goes to position x,y, falls downwards and his/her feet are pointing down. No text box appears, you can flip. In other words, it works well.

However, in methods A and C you can't move until ≈1/2 second later. I thought it was because of the sound, but changed say(-1) to reply(-1) (in method C) and it didn't change anything. I realized later that it's because of the cutscene bars... I'm thinking about endcutscene and untilbars...
After discovering that only method C works well, I tested the x value of gotoposition, seeing exactely where

went using backing. Here's how it works:
gotoroom(0,y) teleports

so that he's centered in the 2nd tile's column, counting from left to right. Raising 1 in the value will result in 1 pixel to the right. Ex: gotoposition(4,y) will teleport Viridian 4 pixels to the right of being centered on the 2nd tile's column (as well as to the defined y position). I don't know what value is the right edge nor if it's possible to use negative values to get o the far left, for example, since I only tested with x=0-5. I don't know how to test y with precision since

falls fast.