Thaeris: I think you've mis-read or are not understanding the Wiki article on Fusion Mortar. "$Shockwave Speed: 0" means no shockwave. Shockwave Radius 0 also means no shockwave.
I read it fully... then checked the actual .tbl file to verify that the data on the Wiki was accurate. FS1's Fusion Mortar does
not have a shockwave radius, but FS2's equivalent certainly does. Furthermore, I don't believe any Fusion Mortar round, FS1/2, had a shockwave speed to it. This is comparable to most fighter-sized weapons... which don't have a shockwave speed applied to them. However, if you're in the blast radius, you're going to feel something. Anyone who's blasted something at close range to pieces with Tempests will know that... in other words, everyone does.

Finally, your comment about "$Shockwave Speed: 0" is invalid
in terms of the Wiki; the wiki article provides no shockwave speed data for the Fusion Mortar. If there is an error with the Wiki, it's that "shockwave radius" pertains to blast radius.