Even though Emilio Vedova, the artist to whom the passage refers, was Venetian, the word "telero" is probably best reserved for the art of the past, at least in an English-language context.

"Telero" is an Italianisation of the Venetian word for a frame ("teler", cf Italian "telaio"), in this case the wooden structure over which the canvas was stretched. As Ambra says, it refers to the work, not the artist.

I would be tempted to translate "cicli di grandi teleri, anche quadrittici" as:

"large-scale painting cycles of up to four canvases"

Note that "panel" might be misleading as it usually means "tavola" in an artistic context.

HTH

Giles