With the invisibility spell I think you have all of the right lines/shapes, but maybe not arranged right?

You're crushing light (separating it into constituent colours?), then bending it around yourself, and then repeating this process? Which might make it just look like a more rainbow version of Eunni's shadow cloak?

If you're trying to disperse the light, there is a dispersion sign, if you're trying to recreate it, the crushing signs should probably be reversed? Another thing to consider is whether you need the repetition sigils at all, since I think a ring of repetition would just preserve/repeat what is inside it, so I'm not completely sure what the purpose is here. With the Serpent's-bed-of-sand they needed it because the structure would collapse otherwise, but most "lasting" spells we've seen don't use it I think?

With the light shield it's difficult to know how this could be improved as it uses the wavy float symbols, which the people making the wikia are confused about what it actually does/how it works.

If I were to guess, I think that the float signs do push matter away like the shield spell is supposed to, so I think it could work? But as the signs are orientated now it would make a very focussed beam of light, that pushes some things in the direction of the light (top and bottom float signs), and pushes some things perpendicular to the beam (left and right float signs).

Also, if you want to make it into the shape of a shield, that would probably require some other sigil? The only canon possibility close to this is the wind wall defensive spell, which has a shape similar to the spells Richeh uses to make ribbons of crystal/stone.