茨 (cí) is the standard syllable Chinese reaches for to render the German/Slavic '-tz' or '-tsch' ending — see also
茨威格 (Zweig) and
莱布尼茨 (Leibniz).
库比茨 reads syllable-by-syllable as Kù-bǐ-cí, suitable for Czech/German names like Kubitz, Kubic, or the front of Kubitschek.