After confirming that the <html> tag inside the <figure> tag was causing the errors with Feedly I went and fixed all posts. Below is the script I ran in the django shell.
Happy to report that Tanzawa is once again producing valid rss.

from bs4 import BeautifulSoup
from post.models import TPost

for t_post in TPost.objects.all():
    entry = t_post.ref_t_entry.first()
    soup = BeautifulSoup(entry.e_content, 'html.parser')
    for html in soup.find_all('html'):
            pic = html.find('picture').extract()
        except AttributeError:
            # no pic
    entry.e_content = str(soup)

Also being able to back up and restore your site's database with a simple "cp db.sqlite3 db.sqlite3.bak" is soooooooo nice.