I had an annoying issue in my lab. Some time ago when I performed vSphere 6.7 PSC convergence my vCenter would stop displaying proper names of tasks in the vSphere Clients UI (both Flex and H5) and show only their placeholders with names like xxx.label.
While there are some KB or communities articles about the issue (and fix) none of them was applicable to my situation (running vCenter Server 6.7U1). I thought that VCSA patches or even deploying new appliance with backup restore would fix it but it did not.
After a little research I found out that the issue is caused by missing catalog.zip file in the /etc/vmware-vpx/locale/ folder. I had another lab with the exactly same vCenter Server build deployed so I just copied that file and transferred it to my vCenter Server Appliance. After service restart via VAMI UI tasks names were back.
I do not know the root cause, but if you have the same issue, give it a go.
Update: 5/6/2021: Diego Holzer emailed me with steps needed to rectify this issue in vSphere 7.0U2a:
During first login, the association files will be cached under /etc/vmware/vsphere-ui/cmCatalog.
BUT not after a restore. I wrote an article for workaround for the version 7.0U2a.
it’s in german, but the workaround works well on English 😃
cd /etc/vmware/vsphere-ui/cmCatalog
wget https://data.vcloud24.ch/bugfix_vcenter_70_label/com.vmware.cis.vcenterserver.zip
wget https://data.vcloud24.ch/bugfix_vcenter_70_label/com.vmware.cis.com.vmware.vsphere.client.zip
chown vsphere-ui:users com.vmware.cis.vcenterserver.zip
chmod 0644 com.vmware.cis.vcenterserver.zip
chown vsphere-ui:users com.vmware.cis.com.vmware.vsphere.client.zip
chmod 0644 com.vmware.cis.com.vmware.vsphere.client.zip
Tom Fojta's Blog 
Hey dad,I read this all and it’s pretty boring! (Not trying to be rude) but it is boring! Can you write something fun! PLZ!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Love your daughter(UnicornAnetaX10Girl)
Hey, thanks for the article, but for those who did not find this article as a solution (like us!), We had the same problem and opened an SR, so I want to explain how we solved the problem.
We have 2 vCenters that are connected to each other (PSC Linked) and one of them had this problem (specifically talking, the problem was with the HTML5 version of VC but not with Flex version). so I compared almost everything (vSphere-ui files and services) between these two VCs and realized that there is a file at this path “/etc/vmware/vsphere-ui/cmCatalog” which is different from the one at the healthy vCenter. The file name was “com.vmware.cis.vcenterserver”, and the difference was the size of files, one of them was almost 5MB and another one (the corrupted one) was 1KB. so we replaced the corrupted one with the file from our good VC and restarted the vSphere Web Client service.
I hope this could be an alternative solution for you guys.
cheers
You can call “/usr/lib/vmware-vpx/py/generateCatalog.py” from a root shell on VCSA, this will re-generate the catalog. Restart services afterwards.