The rest service calls

1. /issue/{idOrKey}/?expand=renderedFields&fields=worklog
2. /issue/{idOrKey}/worklogs

do not provide this.

Call 1. only delivers the first 20 worklogs and does not seem to support pagination

Call 2. delivers them all, but does not have an option to have the wiki-markup rendered as HTML

So either make call 1 have a workLogStartAt Parameter or have call 2 support the expand=renderedFields parameter.

Right now for Jira Cloud i don't know of a way to get worklog comments rendered, for server one would have to implement a service in Java.

A javascript based wiki renderer would help too.