Laundering packages between architectures

[Luna Lucadou]

I was wondering if it's possible to mirror/launder packages between architectures. That is, consider the following:

1. The Linux Mint repos are ia32/amd64 only

2. Certain packages within the LM repos are listed as being compatible with all architectures (e.g. mint-themes)

3. Therefore, if I were to mirror the architecture-neutral mint-themes package in an armhf/arm64-only repo, it would be perfectly fine

I tried to do this with the following command:

$ aptly mirror create -architectures=armhf,arm64 -force-architectures -filter=mint-x-icons,mint-y-icons,mint-themes -filter-with-deps vanessa-crossports http://packages.linuxmint.com vanessa main

It seems to work from the command output. However, when I go to update it to download the packages, I get the following message:

Downloading & parsing package files...
ERROR: unable to update: no candidates for http://packages.linuxmint.com/dists/vanessa/main/binary-armhf/Packages found

So, my question is: Can Aptly do what I'm trying to get it to do?

If not, is there anything that can do what I'm trying to do short of manually downloading packages and using another program to create an apt mirror?

Thanks in advance!