I’m sorry you are having so much trouble syncing with Scrivener.
In regards to your original question, no there isn’t a way to only sync information one-way with Scrivener, or to choose which changes to sync.
You can overall choose which settings to sync (eg. whether to sync certain properties/relationships), however it will sync these for all events.
Rob is correct in that Aeon Timeline considers two “orders”, chronological and narrative.
Timeline, Subway and Relationship view follow the chronological order and Narrative and Outline follow the narrative order.
You can sort the rows of Spreadsheet by certain columns (eg. you mentioned tension), but the “chronological order” of the events does not change, and this is reflected in the “Order” column.
In regards to your information become doubled and mixed up, this could have happened during the syncing process. Sometimes doubles of events can occur if they are not synced correctly to begin with (eg. if you already have events in your timeline that should match a document in Scrivener, but are not chosen to do so. Then the document will create a new event instead, causing a double. This can appear like there is one event in both the Spreadsheet and Narrative, when in fact they are two different events (which is why their summaries may differ if you make changes in one)).
Is it possible for you to send through your timeline file to support@timeline.app ? This will help us work out why the summaries are showing different information. If you could also send through your Scrivener project (or just the .scrivx file which contains the syncing information), then we may be able to get the syncing set up correctly if this is what was causing the issue.