Fetch work item search results: usage of top and changedDate

Hey there,
am trying to find matches for some keywords with fetch_work_item_search_results. Param top within WorkItemSearchRequest is limited to max. 1000, does this mean they're max. 1000 results that can be returned or max. 1000 work items that are even checked?
I'd also like to apply a filter to check only for the work items from the past week, but when adding the filter with System.ChangedDate following exception is thrown:
azure.devops.exceptions.AzureDevOpsServiceError: Unknown filter [System.ChangedDate] found.. Which filter could be used instead or is there no possibility to filter a specific timeframe without using WIQL?

sort_option = SortOption(field='system.id', sort_order='ASC')
for keyword in test_keywords:
    search_request = WorkItemSearchRequest(
        #filters = { 'System.ChangedDate': [ '@Today-7' ]},
        search_text = keyword,
        order_by = [sort_option],
        skip = 0, 
        top = 1000, 
        include_facets = False
    )
    work_item_search_response = search_client.fetch_work_item_search_results(search_request, project=project_name)

Beginne mit den im Issue gezeigten Einstiegspunkten WorkItemSearchRequest und fetch_work_item_search_results und konsultiere anschließend die Dokumentation zur Azure DevOps work item search API für das top-Limit und die unterstützten Filter. Als abgeschlossen gilt die Dokumentation dazu, ob top zurückgegebene oder gesuchte Elemente begrenzt, sowie die Identifizierung der unterstützten Möglichkeit, Ergebnisse nach dem Änderungsdatum einzuschränken, oder eine klare Feststellung, dass WIQL erforderlich ist.