The problem is that AntV L7 appears to be publishing an invalid AMD bundle: it depends on a variety of core-js modules which aren’t available as AMD modules. But those core-js modules aren’t needed anyway, apparently: you can get the module to load just fine by having them all resolve to null using require.alias.
In cases like this, I’d probably fork their repository and then use Rollup to build my own bundle that works correctly. Stackblitz and CodeSandbox effectively do this for you using Webpack, but Observable doesn’t provide a built-in bundler. I’d also consider posting a PR to the L7 repo that fixes the bundle, but I’m not sure what the intent was in crafting the AMD bundle this way.