This does not look/sound like a hot coat/fill coat issue to me.
If you are sanding into the weave, yet there are still shiny depressions directly adjacent to that exposed weave, then your lamination was not pulled tight. Did you use a chipbrush for lamination and if so did you ever pull resin from rails or nose/tail towards middle? Alway pull extra epoxy from middle to edges, and if you need to pull resin inward to saturate areas, use very light pressure on Squeegee/roller/brush to do so then once the cloth drinks in what it wants, go from middle to edges using more pressure incase you pulled the cloth inward. If you need to pull resin back to the middle often, your technique needs more work.
Lamming is not just about saturating the cloth until its clear. You want the weave perpindicular and pulled tight and flat and only enough epoxy applied to saturate the cloth and the wood below. If you use too much epoxy the cloth can float, especially if dry cloth was not pulled tight before. Then when you fill coat it and sand, then you find youself sanding cloth and still have shiny depressions adjacent to that exposed weave.
Lots of techniques that work well or are of no consequence with PE resin on foam do not apply to epoxy on foam or wood.
If your wood was dry when you laminated, this can also pose issues as different areas of the wood suck up more epoxy, makes the cloth look too dry, and you then come back and add more epoxy to these areas and then the cloth might float above of the wood and then ‘perfection’ almost requires starting again from middle pulling towards edges.
Saturating the wood first is an extra step, but then the cloth can easily slide off the board when cutting the laps, and there are potential secondary bonding issues, but it eliminates the issue of some areas of wood being more thirsty than others. Sometimes these extra thirsty areas of wood also swell when they drink in the epoxy which can lift the cloth if done in one step.
Stop sanding into the weave. Scratch only the depressed shiny spots with sharp new uncontaminated paper under a finger. Apply a thicker fillcoat and just accept the glass job will weigh more than it needed to, and is not as strong as it would have been if the cloth was pulled tighter.
Unfortunately the likelyhood of fisheyes/orangepeel is higher now. Might want to use soap and water to remove the any amine blush, dry quickly thoroughly and use gloves and apply antidust techniques.before the next fill coat, and when that fill coat is just barely tacky, perhaps add another atop it, to build the extra thickness so that you do not have to sand into the weave.
But, since the wood is not really going to have a signifiant amount of strength added by the cloth, and the weave will disappear under another layer of epoxy, unless you overheated it sanding, you can get away with sanding into the cloth in some high areas to leessen the amount of shiny depressions. Might save an oz or three of the final weight.
I’ve given up on attaining polyester gloss coat type perfection using epoxy. I will wetsand to 2000 grit or higher if I can find it, then spread a tiny amount of epoxy, 7.5 to 10ML, across one side with a cleaned, thoroughly dried small pore sponge using a lot of pressure to spread the epoxy super thin and flat. I call this a ‘smear coat’ and it yields a pretty gloss epoxy finish with no further work needed. Pretty hard on fingers and wrist and forearms and the boards racks need to be pretty close to nose and tail. Good above and side lighting is required to see any areas were to much epoxy resides and leaves ridges, as well as any potentially dry areas. A month later I might hit it with polish/car wax. It has never flaked off. It can’t compare to a well done PE gloss coat though.
One’s sanding blocks are pretty darned important too. I like using that antislip stuff one puts inside drawers inbetween paper and the sanding block as soon as one finds clumps forming on the sandpaper near the edges, and leaving shiny streaks on the wood. Never use folded sandpaper without a block except on highly curved surfaces like rails or fins, and sometimes not even on those.
if you’re not seeking absolute perfection then the ‘smear coat’ technique works pretty well, in my opinion. The finer the grit of wetsandpaper used the less epoxy needed and the easier it is smeared. use good light and perhaps an extra set of eyes when doing it. Have a new clean dry sponge ready to go if it starts disintegrating. I usually use a piece no larger than 1 inch cubed, and use sharp scissors to remove any corners of the sponge to make it rounder. Squeeze it inside thumb and 2 fingers… Overworking it is to be avoided, as is using too much epoxy. That 7.5ml I quoted, is all i use on one side of a 9’7"x23" longboard’s smear coat. Do not dump the content of mixing cup on the board, but dip sponge in mixing cup lightly and see how far you can smear that amount you picked up.
Doing this smear coat in non humid and warm conditions is also wise, and let it cure much longer than usual before touching it as it is not thick enough to generate any of its own heat.