What is the required action for a Mujtahid when the Qibla is hidden during travel?

Primary text

Anyone knowledgeable about these proofs is a Mujtahid. People of every locality may use local signs, such as specific mountains or rivers, to indicate the Qibla. If the Qibla is hidden from a Mujtahid while traveling and they find no informant, their obligation is to perform the prayer in the direction to which their best judgment leads them. If the proofs are obscured due to cloud cover or darkness, they must exert their effort in determining the direction and perform the prayer, and the prayer is valid because they have expended their utmost effort in seeking the truth while possessing knowledge of the proofs, resembling a judge or scholar when texts are unclear.