After a ton of troubleshooting, yes. Unfortunately, Cloudflare official documentation is at least 16 months outdated. Also, the official README for the ddclient Docker container says to look at Cloudflare documentation.
Anyway, here's the ddclient.conf that FINALLY worked for me! This works with the latest linuxserver/ddclient as of August 19th, 2019.
Pay close attention when commas are used and when they are not.
##
## CloudFlare (www.cloudflare.com)
##
use=web
protocol=cloudflare, \
zone=mydomain.com, \
ttl=10, \
[email protected], \
password=CLOUDFLARE-GLOBAL-API-KEY \
sub1.mydomain.com,sub2.mydomain.com