I can indeed access the data from the CLI, though you might be on to something. I see two sets of tables: one with a capitalized table name and one with a lowercase. For example, Users and users. On my original Bitnami instance, the tables are all lowercase.
mysql> show tables;
±-----------------------+
| Tables_in_mattermost |
±-----------------------+
| Audits |
| Bots |
| ChannelMemberHistory |
| ChannelMembers |
| Channels |
| ClusterDiscovery |
| CommandWebhooks |
| Commands |
| Compliances |
| Emoji |
| FileInfo |
| GroupChannels |
| GroupMembers |
| GroupTeams |
| IncomingWebhooks |
| Jobs |
| Licenses |
| LinkMetadata |
| OAuthAccessData |
| OAuthApps |
| OAuthAuthData |
| OutgoingWebhooks |
| PluginKeyValueStore |
| Posts |
| Preferences |
| ProductNoticeViewState |
| PublicChannels |
| Reactions |
| Roles |
| Schemes |
| Sessions |
| SidebarCategories |
| SidebarChannels |
| Status |
| Systems |
| TeamMembers |
| Teams |
| TermsOfService |
| ThreadMemberships |
| Threads |
| Tokens |
| UploadSessions |
| UserAccessTokens |
| UserGroups |
| UserTermsOfService |
| Users |
| audits |
| bots |
| channelmemberhistory |
| channelmembers |
| channels |
| clusterdiscovery |
| commands |
| commandwebhooks |
| compliances |
| emoji |
| fileinfo |
| groupchannels |
| groupmembers |
| groupteams |
| incomingwebhooks |
| jobs |
| licenses |
| linkmetadata |
| oauthaccessdata |
| oauthapps |
| oauthauthdata |
| outgoingwebhooks |
| pluginkeyvaluestore |
| posts |
| preferences |
| productnoticeviewstate |
| publicchannels |
| reactions |
| roles |
| schemes |
| sessions |
| sidebarcategories |
| sidebarchannels |
| status |
| systems |
| teammembers |
| teams |
| termsofservice |
| threadmemberships |
| threads |
| tokens |
| uploadsessions |
| useraccesstokens |
| usergroups |
| users |
| usertermsofservice |
±-----------------------+
92 rows in set (0.00 sec)