The reason it succeeded in Ukraine and Bangladesh was because of a clear polity divide amongst the population, and huge local support from one of the political sides (including, very importantly, the army), which meant the double goal of (1) getting rid of an "unfriendly" government and (2) installing a "friendly" government could easily succeed. In Sri Lanka and Nepal, it has meant a regime change, but it isn't clear if whoever fomented the "revolution" - the west or the Chinese - have managed to get the desired "friendly" government. However, in all 4 cases, the so-called "revolution" has replaced experienced democratically elected leaders with inexperienced politicians at the helm (which is the second-best option you could hope for, if you can't install a puppet, as inexperienced leaders are more susceptible to political manipulations).
In Iran, what went wrong with this "revolution" is that, first, there is no real local support for pro-west or pro-Israel polity. All those who remember the Shah's regime (when Iran was an ally of the west) and had fond perceptions of the west are now either old or dead. Most of Shah's political supporters were either purged or left with the Shah to the US (or elsewhere). The later, and current, generation has only grown up experiencing American and Israeli hostilities. Along with an understanding of imperialistic history, they despise western attempts of interference in their politics and have no real love for it. Thus, those hoping for a regime change and the installation of the Shah were always delusional that any hostility for the Ayatollah could be translated to support for the west and the Shah. (Moreover, the current "Shah" - the son of deposed Shah - who the west hope to install in power, chooses to stay in US or Europe and thus has no support or understanding of the domestic politics of Iran, and he largely perceived as a puppet of America and Israel amongst the local Iranians).
Second, Trump and Netanyahu's regime underestimated the Ayatollah regime. They figured that just as in Ukraine, Bangladesh, Nepal and Sri Lanka, the government would somehow cave-in under the violent protests rather than opt to suppress the political violence because of the high death toll. Perhaps they might have partially caved-in, if not, for Trump's and Netanyahu's very public "appeal" to the Iranians to "seize the moment" and overthrow the government. This immediately made the Ayatollah regime resolute that the revolution was foreign-instigated, and gave it a public excuse to unleash State violence as an emergency measure (that any State would normally do when faced with a foreign backed insurgency) against protestors. And as Trump's regime claims, the "revolution really failed because the guns that were supposed to be distributed amongst disgruntled Iranians never reached them. Moreover, Iran, that has been surrounded by west and western allies, that has repeatedly sought to undermine it, has been studying western imperialism and destabilisation strategies for decades now. After seeing what happened in Ukraine, Bangladesh, Nepal and Sri Lanka, it probably already had a contingency in place for a similar situation that the west never anticipated.