Base August's only speed feat is intercepting the nuke Laxus shot at Azir, and considering Laxus was hundreds of metres in the air when he did it, August intercepting it is hardly impressive, so is Jellal faster than Base August? Sure, why not, who cares. Red August speed>Jellal speed though.
As for Jellal's strength, meh, Neinhart oneshot him, August low diffed him and his guild, Acnologia oneshot him, so is he strong? I guess, Laxus/Gildarts tier, maybe a bit weaker. Oh and him challenging Acnologia doesnt make him strong, it just means he is stupider than August.