The Living Stream Ministry (publisher of Watchman Nee and Witness Lee) web site is copyright protected and does not contain sufficient information to establish whether they agree or disagree with reformed theology. They appear to uphold an orthodox view of the Trinity and the forgiveness of sins through faith in Christ. Source: https://www.lsm.org/lsm-statement-faith.html
Here is a list of the beliefs of the Local Churches (affiliation) as found in the following Wikipedia article: https://en.wikipedia.org/wiki/Local_churches_(affiliation)#Beliefs
The Bible is the complete divine revelation inspired word by word by God through the Holy Spirit (2 Pet. 1:21, 2 Tim. 3:16).
God is uniquely one, yet Triune — the Father, the Son, and the Spirit (1 Tim. 2:5a, Matt. 28:19).
The Son of God, even God Himself, was incarnated to be a man by the name of Jesus Christ (John 1:1, John 1:14).
Christ died on the cross for our sins, shedding His blood for our redemption (1 Pet. 2:24, Eph. 1:7a).
Christ resurrected from among the dead on the third day (1 Cor. 15:4).
Christ ascended to the right hand of God to be Lord of all (Acts 1:9, Acts 2:33, Acts 2:36).
After His ascension Christ poured down the Spirit of God to baptize His chosen members into one Body and that the Spirit of God, who is also the Spirit of Christ, is moving on this earth today to convict sinners, to regenerate God's chosen people, to dwell in the members of Christ for their growth in life, and to build up the Body of Christ for His full expression.
Whenever any person repents to God and believes in the Lord Jesus Christ, he is regenerated (born again) and becomes a living member of the one Body of Christ (Acts 20:21, John 3:3, Eph. 1:22-23, Rom. 12:5).
Christ is coming again to receive His believers to Himself (1 Thes. 2:19).
The overcoming saints will reign with Christ in the millennium and that all the believers in Christ will participate in the divine blessings in the New Jerusalem in the new heaven and new earth for eternity (Rev. 20:6, 21:2).
Given that Nee and Lee believe that the recovery of “the Lord’s Truth” began with Martin Luther in the Reformation, one would expect that their beliefs are based on Reformed Theology. Here is an extract from a Wikipedia article: https://en.wikipedia.org/wiki/The_Lord%27s_Recovery
The Lord's recovery is a term coined by the Christian preacher Watchman Nee and promoted by Witness Lee that refers to a cumulative recovery of truths lost during what they refer to as the degradation of the church beginning from the second century. Although Nee and Lee recognized that there were recoveries before the time of the Reformation, their opinion was that the Lord's recovery began with Martin Luther in the Reformation because it was from then that significant recoveries were made.
The article lists many individuals considered to have contributed to the recovery. Here are a few:
John Calvin; John Wesley, Charles Wesley, and George Whitefield recovered the matters of salvation, eradication of sin, sanctification, and open-air preaching; Bible expositors among the Brethren such as John Nelson Darby... Other people considered to be part of the Lord's recovery include Johann Arndt, Theodore Austin-Sparks, Margaret E. Barber, Bernard of Clairvaux, Jacob Boehme, Peter Böhler, John Bunyan, Brother Lawrence (Nicholas Herman), Jan Hus, George Henry Lang, William Law, Dwight Lyman Moody, Charles Haddon Spurgeon, William Tyndale, John Wycliffe, and Aiden Wilson Tozer.
They even have their own translation of the Bible: https://en.wikipedia.org/wiki/Recovery_Version#Translation
The Recovery Version is a recent translation of the Bible from the revised 1990 edition of the Hebrew Scriptures, Biblia Hebraica Stuttgartensia, and the Nestle-Aland Greek text as found in Novum Testamentum Graece (26th edition)... The Recovery Version claims to avoid biases and inaccurate judgments and to express the message of the Bible in English as accurately as possible. As such, it departs from traditional renderings in certain passages. Its translation is essentially literal/word-for-word/formal equivalent, seeking to preserve the wording of the original Hebrew or Greek text and the personal style of each biblical writer. Its translation is intended as transparent; interpretive ambiguities present in the original text are left unresolved in this translation for the readers to consider. The Recovery Version renders the Tetragrammaton as Jehovah throughout the Old Testament.
One of the major difficulties in trying to answer a question like this stems from the lawsuits brought against churches, publishers and individuals who criticise this organisation. Here is a short extract from a lengthy article that examines the subject in detail: https://www.gotquestions.org/Witness-Lee-local-church.html
The history of the conflict between Witness Lee and his Local Church movement—also known as the “Lord’s Recovery Movement,” along with their publishing arm, Living Stream Ministry (LSM)—and the counter-cult establishment is far too long for a detailed recounting here, but those who are interested in the full story can access it through the CRI website http://journal.equip.org/issues/we-were-wrong
The articles goes on to look at four areas of concern, namely: the nature of God, the nature of man, the legitimacy of evangelical churches and denominations, and the lawsuits brought against Evangelical churches, publishers and individuals by the Local Church. The article concludes:
What is the conclusion of the matter, and what are Christians to believe about Witness Lee and the Local Church movement? Elliot Miller, editor-in-chief of the Christian Research Journal, declares at the end of the 50-page treatment “We were wrong” and concludes that the Local Church is not an “aberrant Christian group” but a “solid orthodox group of believers.”
Another useful source of information comes from the Christian Research Institute - The “Local Church” as Movement and Source of Controversy (2011): https://www.equip.org/article/the-local-church-as-movement-and-source-of-controversy/
With regard to the question about the theology of this group, I don’t think I want to raise my head above the parapet (spiritually speaking) in case I get shot at. Suffice to say that people are at liberty to draw their own conclusions, although trying to establish the facts in relation to their theology is neither easy nor straightforward.