The Historical Languages & AI 2026: Conference Companion serves as a supplementary volume to the international conference held at Humboldt-Universität zu Berlin on March 5–6, 2026. Edited by the Daidalos Project and funded by the German Research Foundation (DFG), the volume is published via Zenodo to provide a record of ongoing research, workshops, and preliminary findings that complement the long papers presented in the official conference proceedings. The companion highlights the evolving intersection of Natural Language Processing and classical philology, focusing on the development of resources for historical languages. It includes three primary sections: Short Papers: These contributions address specific linguistic and computational challenges, such as the creation of gold-standard corpora for Medieval French (ALMeD), the construction of a unified Old Church Slavonic corpus for NLP tasks, and the probing of sentence embedding robustness for intertextuality detection in Latin. Workshop: A dedicated workshop explores the development of LLMs tailored specifically for ancient scientific and technical texts. Research Pitches: Brief presentations introduce projects like PathFinder.AI for migration studies, the COALA project for Latin semantics, and the TESLA initiative for establishing technical standards in Digital Classics.