CRM for JIRA web section can recognize reporter's company if the reporter has company set in Contacts Directory
If the contact doesn't have company linked, you can create new company for the contact right from issue. Let's take contact Alexander Plotnikov for example:
Alexander reported an issue and he doesn't have linked company in Contacts Directory (see screenshot above). Click on "Create Company", type in new company name and click on "Save".
Use "Create company" button in web section only for creation of new companies which are not listed in Company directory yet. If you type in existing name from Company directory, another company with the same name will be created.