Yes, the tape is plenty.
In fact that's all that holds them on.
The holes are simply for alignment.
To make sure each GT emblem or pony are always in the same place.
And there are two different size holes to make sure none are put on upside down.
I'm pretty sure most of the emblems on my dad's 4Runner don't have alignment holes. I guess it's just faster and easier on the assembly line, hell get a robot to do it. I hate holes just punched in sheet metal, makes it harder to do a simple badge delete.