What is a "traditional engine"?
A traditional engine (hand-crafted evaluation, HCE) is an engine that uses traditional evaluation (also called hand-crafted evaluation) rather than neural network evaluation, such as Mingshou 326 (名手 326), NewGG, and early versions of Xuanfeng (旋风).
The playing strength ceiling of traditional engines is much lower than that of NNUE engines, but they search faster than NNUE engines.
Traditional evaluation is written by hand and is interpretable (meaning the purpose of each evaluation term can be explained, for example how many points each piece is worth, when a Chariot gets a bonus or penalty at certain squares, a penalty for the General being advanced, and a penalty for a blocked Horse), while neural-network-based evaluation is not interpretable.
Simple traditional evaluation usually consists of piece values and PSQT (piece-square tables, which account for piece positions). Complex traditional evaluation can also consider piece mobility, pins, General safety and so on.