Is consenting to the writing of the name "Jisr" (bridge), with the intention of viewing its image, considered major disbelief or mockery of Allah, such that it amounts to major disbelief?

What the questioner mentioned about himself is by no means disbelief. His question stems from intrusive thoughts (waswasah) concerning disbelief. The cure for intrusive thoughts is to completely disregard them, pay no attention to them, and refrain from asking about them, all while supplicating earnestly to Allah. Ibn Hajar al-Haytami advised that the remedy for intrusive thoughts is to ignore them, and that whoever listens to them will find them increasing until they lead to madness. He also stated that whoever is afflicted with intrusive thoughts should seek refuge in Allah and desist from them. Intrusive thoughts are from Satan, who wishes to lead the believer into misguidance and confusion. Al-Izz ibn Abd al-Salam mentioned that the cure for intrusive thoughts is to believe that they are satanic whispers, and by fighting them, one earns the reward of striving.