How do JW reconcile that their foundational belief about Worship of Christ made them idolatrous?

Charles Taze Russell, 'Judge' Rutherford, and Nathan Knorr did indeed promote the belief that Jesus Christ should receive some form of worship, even though they also taught that this Jesus was a creature - created by Jehovah God as Michael, the Archangel. Two distinct deities receiving worship is, indeed, idolatry. That was the one and only direct, solo creation of Jehovah, they say (and continue to say to this day). It was Michael who was used by Jehovah to then create all the other angels, and this universe, this world, and all life on it.

Although the Bible Students were trinitarian to begin with, due to claiming that the one who became Jesus had a starting point in time, they could not hold on to trinitarianism, but had to let go of that. It took a long time. It had to be done very gradually so as not to lose their rapidly growing membership. They had suffered huge losses when Rutherford took over from the deceased Russell. Once they'd got over that by calling the departed ones the "wicked servant" class of Matthew 24:48-51, and claiming themselves to be "the faithful and wise servant" (vss.45-47), they had established a base upon which to build. Then they began to change various doctrines, e.g. only 144,000 people from earth would get to heaven; the great crowd, who Russell had said would be a separate group in heaven, were actually never going to heaven - their hope would be to live on a paradise earth. Then they said that as only those with the heavenly hope had indwelling 'holy spirit', the majority were not in the New Covenant. Those with the heavenly hope were, and so must be obediently supported and followed. Only those few could take bread and wine when remembering Christ's death. That was in place by the mid 1930s.

I detail this to show how long it took for such doctrinal changes to become unquestioningly accepted. Because their leaders had gradually led them into accepting that Christ should not be worshipped (by the early 1950s) and then by coming out with their own version of the New Testament, very few noticed what was really going on - taking the wind out of the sails of those who accused them of idolatrous polytheism. For the duration of the decades where they said Jesus was created, but where they also claimed to worship Christ, they could be accused of idolatry (and were), for their Jesus was created by Almighty God. By saying Jesus was 'a god', they had a Big God and a little god. Two gods. Idolatry if both were worshipped.

That's why it took so long for the official Charter to get changed to accord with what they had been teaching about not worshipping Christ. The ground had been prepared over a long time, the change to doctrine introduced and accepted, then the final stage was changing the Charter (which hardly any Witness would ever have seen, let alone spot a massive change to.)

But the Witnesses simply believe that Jehovah is very patient with them, gradually leading them into a purer state. They quote Proverbs 4:18, that the path of the righteous is like the first ray of dawn, the way getting brighter and brighter until it is fully day. Every time they introduce either a new teaching, or a change to an old one, they use that Proverb, and because the leaders have indwelling 'holy spirit' while 99% of the rest do not, their every word is accepted unquestioningly.

This is obviously not an explanation written by a Jehovah's Witness, but it is based on nearly 60 years direct experience of them. After all, my parents first became Jehovah's Witnesses in the mid 1930s, as some of the first of the new 'Jonadab' class, who could not take bread and wine at the memorial. I've fallen heir to a lot of very old literature whereby changes can be traced. Sometimes Jehovah's Witnesses do not believe quotes I use from that literature; they are so scandalized by seeing what used to be taught, they claim I've got corrupted sources (on-line) but I work from authentic publications their own Society printed. And I expect I will be viewed by them as part of "that wicked servant" class. That still remains a strong tool for keeping members from checking things out for themselves.

Thus all Witnesses today will laugh at any claim they used to be idolatrous. "Oh, we were just tainted with Babylon the Great back then but Jehovah gradually made his light shine brighter so that we left worship of Christ completely. He hasn't got any worship from us since the 1950s. What are you digging the past up for?" You ask how they can reconcile that matter. "There's nothing to reconcile", they suppose.

EDIT: official JW sources re. worship of Christ in the Trinitarian sense: Zion's Watch Tower 1892, May 15 p.157 (from "His Divinity was retained in humanity... [to] receiving worship.")

Vindication book 1931, Vol. 3 p. 295 (God's people will worship Jehovah and Jesus during the Millennium.)

Watchtower 1939 Nov. 15 p. 339 (sentence beginning "Jehovah God commands all to worship Christ Jesus...")

Re. the Holy Spirit, prior to demoting him to an 'it', as in 'holy spirit': The Divine Plan of the Ages, Series I of Studies in the Scriptures, 1889, pp. 89 & 280 as mere random examples of how, throughout the book, distinction is made between "your being born a new spirit creature, a spirit being, in the first resurrection" and "the condition of those born of the Spirit" (as in John chapter 3), and of "the descent of the Holy Spirit at Pentecost".