Hi
I do not know the details of i2pd package.
For stretch we generally update only due to security reasons. There are exceptions, but it needs to be a really good one. Like "if we do not update the package is useless or severely crippled".
What you describe does not strike me as something that warrant an update. But maybe there is more to it than I understood. As I said I'm not someone who knows i2pd.
Another thing is that you also need to convince stable release managers first, because we do not want to update oldstable if not stable is updated.
Cheers
// Ola