What problem does your feature solve?

Avoids use of parent, which is vague in this context.

What would you like to see?

Use host function names that reflect the envelope type names, such as create_contract_from_contract or create_contract_from_ed25519. Any changes should be reflected in rs-stellar-contract-env and rs-stellar-contract-sdk as well.

What alternatives are there?

Leave it as is. Choose a different naming scheme entirely.