The GB is wrong about so many things, including the plague after the locusts...
The next "plague" after the locusts is just another perspective of the same event, the attack on religion, from a different angle...
"The one woe is past. Look! Two more woes are coming after these things. The sixth angel blew his trumpet. And I heard one voice from the horns of the golden altar that is before God say to the sixth angel who had the trumpet: “Untie the four angels who are bound at the great river Eu·phraʹtes.” And the four angels who have been prepared for the hour and day and month and year were untied to kill a third of the people.""
The angels who are "bound at the great river Euphrates" are the same as the angels referred to in this verse:
"After this I saw four angels standing on the four corners of the earth, holding tight the four winds of the earth, so that no wind could blow on the earth or on the sea or on any tree. And I saw another angel ascending from the sunrise, having a seal of the living God; and he called with a loud voice to the four angels to whom it was granted to harm the earth and the sea, saying: “Do not harm the earth or the sea or the trees, until after we have sealed the slaves of our God in their foreheads.”" (Revelation 7:1-13)
The "great river Euphrates" was by Babylon.
The angels have been holding back the winds of destruction from Babylon the Great. The locust plague is the attack on Babylon the Great. The plagues are just different aspects of the fall of Babylon the Great and other events of the 3 1/2 year great tribulation that hasn't yet begun but will soon.
"And now you know what is acting as a restraint, so that he will be revealed in his own due time. True, the mystery of this lawlessness is already at work, but only until the one who is right now acting as a restraint is out of the way." (2 Thessalonians 2:6,7)
The "restraint" is the angels.
Some more from 2 Thessalonians chapter 2...
"However, brothers, concerning the presence of our Lord Jesus Christ and our being gathered together to him, we ask you not to be quickly shaken from your reason nor to be alarmed either by an inspired statement or by a spoken message or by a letter appearing to be from us, to the effect that the day of Jehovah is here." The GB/FDS said "the day of Jehovah" (aka Jesus getting the kingdom) began in 1914. The GB/FDS have an appearance of godly devotion but prove false to its power.
"Let no one lead you astray in any way, because it will not come unless the apostasy comes first and the man of lawlessness gets revealed, the son of destruction. He stands in opposition and exalts himself above every so-called god or object of worship, so that he sits down in the temple of God, publicly showing himself to be a god. Do you not remember that when I was still with you, I used to tell you these things?" The GB/FDS wants to be worshipped ahead of God. The GB/FDS are apostates.
"And now you know what is acting as a restraint, so that he will be revealed in his own due time. True, the mystery of this lawlessness is already at work, but only until the one who is right now acting as a restraint is out of the way. Then, indeed, the lawless one will be revealed, whom the Lord Jesus will do away with by the spirit of his mouth and bring to nothing by the manifestation of his presence." At the great tribulation, the angels will not hold back the UN from attacking religion anymore. During that attack, Jesus will allow the GB/FDS JWborg (as well as all other groups claiming to be Christian) to be cleaned out of their properties and prominence just like Jesus cleaned out the temple in the first century. The independent religious institutions themselves will be completely gone.
"But the lawless one’s presence is by the operation of Satan with every powerful work and lying signs and wonders and every unrighteous deception for those who are perishing, as a retribution because they did not accept the love of the truth in order that they might be saved. That is why God lets a deceptive influence mislead them so that they may come to believe the lie, in order that they all may be judged because they did not believe the truth but took pleasure in unrighteousness." Satan has allowed the JWborg people to say "1914, see we predicted it!" just like Satan empowered Jannes and Jambres to seem to make frogs and some of the plagues in the Egypt. Satan is the one who lined up the nations for their WWI battles, just like playing out a war game.
The angels of the congregations know where Christians are. The congregations of Revelation stand for all the religious groups that claim their descent from Christ's first century congregation. Revelation chapters 2 and 3 shows there is sectarianism in some, and idolatry in some, and immorality in some. When Jesus takes the throne, he will send out his angels and they will remove the weeds and gather the wheat in bundles. The leaven of the false teachings will be removed. The Christian congregation will be refined and restored by the 1,150th day of the tribulation.
"Out of one of them came another horn, a small one, and it grew very great toward the south and toward the east and toward the Decoration. It grew so great that it reached all the way to the army of the heavens, and it caused some of the army and some of the stars to fall to the earth, and it trampled them down. It exalted itself even against the Prince of the army, and from him the constant feature was taken away, and the established place of his sanctuary was thrown down. And an army was given over, together with the constant feature, because of transgression; and it kept throwing truth to the earth, and it acted and had success. And I heard a holy one speaking, and another holy one said to the one speaking: “How long will the vision of the constant feature and of the transgression causing desolation continue, to make both the holy place and the army things to trample on?” So he said to me: “Until 2,300 evenings and mornings; and the holy place will certainly be restored to its right condition.”" (Daniel 8:9-14)
The UN is the horn. Genesis says "An evening, a morning, one day." An evening is half a day. A morning is half a day. 2,300 half days is 1,150 days.
We will have to keep announcing at that point that Jesus is king in heaven and that he is coming. There will be a great crowd of former unbelievers during the tribulation that say "we will go with you people, for we have heard that God is with you people," just like there was a great crowd of unbelievers in Egypt who didn't have time to "convert" to the Israelite religion but were still saved.