Each manufacturer has their own limits on flatness. On the floating floor I did install, neither the foam nor the top layer (mine was actually wood but installed and locked together like many laminates) are often attached to anything. So, if yours is like mine, you don't need to attach anything to anything. The distributed weight of the whole thing and the friction between the laminate and the foam and the foam to the floor keep it in place.
I will, though, again warn you about the overall flatness...it is pretty strict, and your tile may or may not actually be flat enough. Many tile has a slight dome shape, and the grout may not be level with the top of the tile. Plus, at least on the one I installed, it had to be flat to within 1/8" over 10'. If an edge happened to align with that low point, you might delaminate the flooring which is the reason they want it really flat. Some will allow you to use something like a layer(s) of roofing felt to help fill in a depression (sort of like contour lines on a topographic map), but a hump could be lethal to the floor.
This is more a question of contacting the manufacturer and reading the instructions carefully. If the overall tile floor is flat enough, squeegeeing in a leveler to fill in the grout areas shouldn't be all that hard to do.
Verify with the manufacturer what their recommendation are.
Cutting laminate material requires a very sharp blade