That means cusp of recession, as in being on it.

Germany on cusp of recession, says ifo, after business sentiment falls – German business morale fell more than expected in July as high energy prices and impending gas shortages push Europe’s largest economy to the cusp of recession, a survey showed on Monday.
The Ifo institute said its business climax index was 88.6, its lowest level in more than two years. June had also seen an unexpected drop to a downwardly revised reading of 92.2.
I would translate Schwelle as Threshhold rather than Cusp. Change of meaning.