What principles should I follow when entering data into a complex relational database?
A foreign key relates to the primary key of another table. When the record with the foreign is entered, the corresponding record with that primary key must be present. Therefore you must always start by inserting in the tables on the 1-side of the relation (the master or parent or primary key table). Then only you can enter a record on the n-side of the relation (into the detail or child or foreign key table).

Order: 1. Entry, 2. Keyword, 3. Keyword_Priority.

If a table has several foreign keys, then the related records in all the other tables with the corresponding primary keys must be entered first. For instance, before entering a record into SenseRestricted..., the corresponding records in Sense and in Reading must have been inserted.