Is your question can a web adapter be used when running in Edge IE Compatibility mode? No, however support can help you convert a legacy web adapter to a UWA Edge IE Compatibility adapter. Open a support ticket to start the process.
If your question is, can a legacy web adapter be converted to run in Edge (not in compatibility mode)? No, legacy web adapters and UWA adapters use different match rules and there is no way to directly convert between the two.