Spongeforge 2705 is crashing when booting up due to the between lands (version 3.3.10) world gen
crash report : https://pastebin.com/yP9H9k8M
Are you sure it’s the Betweenlands mod? You have a number of coremods there that could also cause issues.
You are actually using spongeforge-1.12.2-2705-7.1.0-BETA-3361, with Forge 2750, according to the log. The spongeforge version you are using was built against Forge 2705; there may have been breaking changes in Forge - have you tried rolling back Forge?
with the new sponge that was release a couple of hours ago seems to be working.