Higher-strength bolts (like A325) are likely to be heat-treated and/or strain-hardened material, so it's not just a welding issue, it also involves strength properties of the bolt itself.
Confirm with the designer what is needed. Possibly weld a clip of some kind with the bolt going through it.
You can thread rod produced to A36 or similar, or get anchor bolts that are basically A36 (and may or may not be dual-certified as such)- and that might be a better solution.
Sometimes people figure "stronger is better" and specify higher-strength stuff when they don't need it just because.