Here is the Log Skeleton model generated for the given process variants:

```python
log_skeleton = {
    'equivalence': {('Create Fine', 'Create Fine'), ('Send Fine', 'Send Fine'), ('Insert Fine Notification', 'Insert Fine Notification'), ('Add penalty', 'Add penalty'), ('Payment', 'Payment'), ('Send for Credit Collection', 'Send for Credit Collection'), ('Insert Date Appeal to Prefecture', 'Insert Date Appeal to Prefecture'), ('Send Appeal to Prefecture', 'Send Appeal to Prefecture'), ('Receive Result Appeal from Prefecture', 'Receive Result Appeal from Prefecture'), ('Notify Result Appeal to Offender', 'Notify Result Appeal to Offender'), ('Appeal to Judge', 'Appeal to Judge')},
    'always_before': {('Create Fine', 'Send Fine'), ('Send Fine', 'Insert Fine Notification'), ('Insert Fine Notification', 'Add penalty'), ('Add penalty', 'Payment'), ('Payment', 'Send for Credit Collection'), ('Insert Fine Notification', 'Insert Date Appeal to Prefecture'), ('Insert Date Appeal to Prefecture', 'Send Appeal to Prefecture'), ('Send Appeal to Prefecture', 'Add penalty'), ('Add penalty', 'Receive Result Appeal from Prefecture'), ('Receive Result Appeal from Prefecture', 'Notify Result Appeal to Offender'), ('Notify Result Appeal to Offender', 'Appeal to Judge')},
    'always_after': {('Create Fine', 'Send Fine'), ('Send Fine', 'Insert Fine Notification'), ('Insert Fine Notification', 'Add penalty'), ('Add penalty', 'Payment'), ('Payment', 'Send for Credit Collection'), ('Insert Date Appeal to Prefecture', 'Insert Fine Notification'), ('Send Appeal to Prefecture', 'Insert Date Appeal to Prefecture'), ('Add penalty', 'Send Appeal to Prefecture'), ('Receive Result Appeal from Prefecture', 'Add penalty'), ('Notify Result Appeal to Offender', 'Receive Result Appeal from Prefecture'), ('Appeal to Judge', 'Notify Result Appeal to Offender')},
    'never_together': {('Payment', 'Payment'), ('Payment', 'Payment'), ('Payment', 'Payment'), ('Send Appeal to Prefecture', 'Receive Result Appeal from Prefecture'), ('Add penalty', 'Notify Result Appeal to Offender'), ('Appeal to Judge', 'Notify Result Appeal to Offender')},
    'activ_freq': {'Create Fine': {1}, 'Send Fine': {1, 2}, 'Insert Fine Notification': {1}, 'Add penalty': {1}, 'Payment': {1, 2}, 'Send for Credit Collection': {1}, 'Insert Date Appeal to Prefecture': {1}, 'Send Appeal to Prefecture': {1}, 'Receive Result Appeal from Prefecture': {1}, 'Notify Result Appeal to Offender': {1}, 'Appeal to Judge': {1}},
    'directly_follows': {('Send Fine', 'Insert Fine Notification'), ('Insert Fine Notification', 'Add penalty'), ('Add penalty', 'Payment'), ('Insert Fine Notification', 'Insert Date Appeal to Prefecture'), ('Insert Date Appeal to Prefecture', 'Send Appeal to Prefecture'), ('Send Appeal to Prefecture', 'Add penalty'), ('Add penalty', 'Receive Result Appeal from Prefecture'), ('Receive Result Appeal from Prefecture', 'Notify Result Appeal to Offender'), ('Notify Result Appeal to Offender', 'Appeal to Judge')}
}
```

This Log Skeleton model captures the constraints and dependencies observed in the given process variants.