Sticking with the supplies you have you should be able to rectify this without too much difficulty. One final coat of varnish should do it, with or without a light overall sanding using your 320.
If you do sand don't just target the trouble spots, as tempting as that is. And do sand very lightly, using basically no pressure — "just the weight of your arm" is a common guideline given. You're not aiming to make the surface uniformly dull, just flatten it a little IF there's more texture there than this one photograph shows. On the other hand, if the surface texture is actually very fine you can probably safely skip the sanding and proceed directly to varnishing.
Obviously you have to apply this last coat carefully to ensure the surface quality you want, and this is certainly possible using the gel topcoat straight from the tin. But if the goal is to use the final surface pretty much as-is1 my experience has been that the most forgiving product for this, by quite a margin, is wiping varnish.
Make wiping varnish
Now a gel varnish is not the ideal candidate for conversion to wiping varnish (normally it's done starting from regular fluid varnishes) but the product will still dilute and thin in consistency when mixed with mineral spirits and therefore can be applied this way, despite it being outside of its normal parameters.
I can't give you a formula for how much to thin since I don't know the exact consistency of the GF product, but you merely need to aim for a given viscosity. Think more skimmed milk than heavy cream. But this is approximate so don't sweat hitting some target accurately, just dilute a little at a time until you get to around this mark.
Make sure the gel topcoat is thoroughly mixed before you start. I can't stress this enough, as you're using a satin it contains some matting agent which has to be uniformly distributed.
Don't thin in the original container. Dilute in any clean glass jar with a tight-fitting lid you have that's not too small, transferring some gel topcoat to it and then adding mineral spirits and stirring thoroughly, or, better, shaking the jar once tightly capped2. A spoon is great for transferring varnish BTW, but make sure you clean it thoroughly afterwards if you want to use it again for its original purpose LOL
Make more than you think you need, to ensure you don't run out as you spread it over the surface. I'm thinking maybe 1/3 to 1/2 a cup (80-120ml) depending on the size of the table. But if you did run out it's hardly a disaster, you could make another batch in under a minute.
Get it on, wipe it (mostly) off. Wipe or brush or roller it on to the surface; it doesn't really matter how you apply it, just get it on there. Then carefully wipe most of it off — it's this last step that makes wiping varnish so nearly foolproof, since a very thin wiped-off layer usually dries uniformly and with minimal risk of dust nibs because it also dries so quickly3.
With luck this single application of wiping varnish will do what you're looking for here. If not, a second layer will do the trick.
1 Minus some very minor de-nibbing, which may or may not be needed. If you do need to de-nib, as odd as it might sound the rough side of brown paper is perfect for this. And yes, you can use a grocery bag if that's the only brown paper you have :-)
2 You don't need to worry about the bubbles created if you shake the jar, because the wiping process and the thin consistency ensures that no bubbles will survive in the applied varnish.
3 No longer wet in well under an hour, much reduced tackiness within about three hours and tack-free within 6-9 hours, depending on a few variables.
