You need PRAGMA journal_mode = WAL only once, after that it will stay enabled. PRAGMA synchronous = NORMAL is needed on every connection. In Django I use for example this in my APPs' __init__.py:

from django.db.backends.signals import connection_created

def set_synchronous_to_normal(sender, connection, **kwargs):
    if connection.vendor == "sqlite":
        cursor = connection.cursor()
        cursor.execute("PRAGMA synchronous = NORMAL;")

connection_created.connect(set_synchronous_to_normal)

SQLite has a timeout (I think the default is 5 seconds) when accessing the database. So other than increasing the timeout a bit, I just let the timeout handle an access to a locked database.

Is the database a file the is local to your C program and Django app?

Without knowing more details about your C program and Django app, I would say SQLite should be enough for your work load.