Before Rāmānuja, it was Bhāskara who referred to māyā-vādin-s as bauddha-matāvalambin. Please see Chapter XV (The Bhāskara School of Philosophy) in A History of Indian Philosophy (Volume 3), where Dasgupta writes
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Thus, at the very beginning of his commentary, he says that it aims at refuting those who, hiding the real sense of the sūtra, have only expressed their own opinions, and in other places also he speaks in very strong terms against the commentator who holds the māyā doctrine and is a Buddhist in his views[3].
[3] sūtrā-bhiprāya-saṃvṛtyā svābhiprāyā-prakāśanāt, vyākhyātaṃ yair idam śāstraṃ vyākhyeyaṃ tan-nivṛttaye. Bhāskara’s Commentary, p. i.
Also “ye tu bauddha-matāvalambino māyā-vādinas te’pi anena nyāyena sūtra-kāreṇai’va nirastāḥ.” Ibid. II. 2. 29.
In another place Śaṅkara is referred to as explaining views which were really propounded by the Mahāyāna Buddhists—vigītaṃ vicchinna-mūlaṃ māhāyānika-bauddha-gāthitaṃ māyā-vādaṃ vyāvarṇayanto lokān vyāmohayanti. Ibid. 1. 4. 25.
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