first of all, you appear to be as crazy as I am: we are both trying to run a 1.7.10 pack (though I hope you realize, as I do, that getting support is going to be nearly impossible for that reason). Second of all, did you happen to notice the prompt that shows up when you start the corresponding game client (I know you said you are running a server but you should see the message when you eventually try to load the game in order to connect) asking if you want to download CodingLib? That dependency is missing and even if you click yes on the prompt, it won't be able to download automatically because the site it's supposed to retrieve it from is, as far as I can tell, no longer online.
I'm not sure if there's still an official place to find that library (other than the site that's no longer online), so your best bet might be to disable voltz engine and hope it's not needed for any mods you can't live without. Unless of course you can find the exact version you need and shove it into your ./mods/1.7.10 folder manually...
edit: I found a suitable version of Coding Lib in the support channel of Built Broken's discord. 2.8b50 and worked for 1.9.14b302 (the oldest version I could get in my profile through the curseforge app), but if that doesn't work for whatever build you are running, there may be others lying around somewhere.