Even at 4 replacements in an update pack that is 104 cards per set which is more or less a core tome 1 spell set and that without any of the level 1s getting 6.
So instead of using those print runs to print new cards they are reprinting old cards.
This is the big problem. Printing "errata" replacement cards really does cost time at graphics, typesetting and printers. Sure, it doesn't take up development time, but it could still mean a delay in other product. Of course, updated card text should show up on future printings of the product in which it's contained, just like each printing of the core set, the latest printing of FvW (e.g. Goblin Builder), etc.
That said, there was a long wait between Forged in Fire and the releases that followed (Battlegrounds Domination/Academy/Paladin vs Siren/Lost Grimoire v1). If there might be another year-plus long wait between expansions, perhaps a "Core Spell Tome 3" that includes errata + staples could be produced, which might include latest card text for some cards and extra copies of staples like Teleport, Lesser Teleport, Force Push, Disperse, Crumble, Mage Bane, Ghoul Rot, Acid Ball, Brace Yourself, Leather Chausses, etc. But only if it doesn't take time/effort away from future new release expansions... and perhaps even reprints (e.g. keeping core sets and previous expansions in stock), since Mage Wars could really use new players, and new players need Core Sets and main expansions, not errata reprints.