First of all, thank you for your feedbacks.
Since my first post, I know that th SQLite3.dll supports the FTS5 extension. What I've discovered is, I need to change some PRAGMA and parameters under my Pascal source to "activate" this FTS5 features.
Here is my code :
Before the connection
...
ProviderName := 'SQLite';
SpecificOptions.Add('EnableLoadExtension = True');
SpecificOptions.Add('Direct = True');
SpecificOptions.Add('EnableSharedCache = True');
SpecificOptions.Add('ReadUncommitted = True');
SpecificOptions.Add('BusyTimeout = 3000');
...
After the connection
...
ExecSQL('PRAGMA cache_size = 400000;');
ExecSQL('PRAGMA synchronous = OFF;');
ExecSQL('PRAGMA journal_mode = OFF;');
ExecSQL('PRAGMA locking_mode = EXCLUSIVE;');
ExecSQL('PRAGMA count_changes = OFF;');
ExecSQL('PRAGMA temp_store = MEMORY;');
ExecSQL('PRAGMA auto_vacuum = NONE;');
ExecSQL('PRAGMA enable_fts5;');
For the last line, I've tried different syntax like:
ExecSQL('PRAGMA enable_fts5 = ON;');
And
ExecSQL('PRAGMA enable_fts5 = TRUE;');
All this ExecSQL lines doesn't break my runtime module.
After that, what I read is to apply this "SELECT" to activate at least, the FTS5 features :
ExecSQL('SELECT load_extension("SQLite.dll", "sqlite3_fts5_init");';
At this point, my application breaks on this line.
If I don't use this last line, my INSERT command under my FTS table breaks with this message : "No such module : FTS5"
As I already said, I've spent a lot of time under so many SQLite forums and Pascal/Delphi too...
What I can add too, under the SQLite Manager, using the same SQLite3.dll, by using script SQL, my INSERT command works find.
So, if someone has a tip or suggestion, I'll take it.
Once again, thank you all for your help.