it is also above my pay grade, mainly due to my position as being volunteer so technically everything is above my pay grade, but as mentioned a ticket would be the best option
step 1. delete optifine step 2. use performance mods designed to be used with sodium https://modrinth.com/user/jellysquid3 and if you want shaders then add oculus/iris
is there anything in the log that gives anything interesting? also have you tried with only DH installed and you may get better support if you joined the discord
i cant speak for the others and I don't 100% know how many download buttons you can have but if there can only be 1 download button maybe make a public google drive or pastebin/google docs or similar with the links to each different version or skip the download button directly and just use the description to post the individual download links
download the curseforge launcher and install a performance pack such as fabulously optimized and immersed in shaders, I would recommend the first pack to anyone who wants to try a vanilla experience without the performance of 1.13+. if anyone knows what happened in performance from 1.12-1.13+ well that's another can of worms but in short for most people performance dropped by half
good mod choices for 1.12 and under, anything over that and there are better replacements for almost every mod listed
optifine has been replaced with sodium and its forks
biomes o Plenty and Journymap are still good, tinkers has gone to garbage and the system we all know and love has been thrown out in favor of being more simple making way for silent gear Twilight Forest is starting to show its age and has been the same for pretty much the last few major versions of minecraft pams harvest craft and its v2 for 1.14-1.16 is still good, croptopia is kind of a replacement for newer versions
to manually set the link <-- just leads back to this page