Having done something similar, but entirely different, several times, I'm surprised you didn't choose to slowly refactor the code to be more and more native C# over time. iYou start with 100% Wasabi / 0% C# and slowly work up the native C# parts, in code units, until you reach a level sufficiently high to feel confident to do a final push to switch entirely to C#.

(In my experience, you need to build up an inter-op layer first to make working in C# somewhat sane, but it's usually not hard to identify the necessary helper modules needed. Having the .NET runtime actually is a boon here since the IL is designed for inter-language inter-op.)