From having had read all 250+ issues of Flash Vol 2, the speedsters seem to still be aware of each other’s speed even whilst accelerated. Many times, the many speedsters’ connections to the Speed Force differ, so some wielders have at times been faster than others. Their perceptions also increase to superhuman speeds, yes, so they can see each other clearly (most of the time) without only seeing blurs, but the scenes typically don’t look like normal humans having a melee fight while everyone else is seemingly frozen in time. I mean, I haven’t once seen a speedster battle in all those issues wherein the speedsters stood and stayed in the same area while fighting each other. They tend to run whilst delivering blows, which seems to be a universal fighting style among speedsters.
Short answer: Even while two speedsters are using their speed, no, the fights generally do not “appear” graphic-wise as two normal people having a fight.