Yes, the apostles were eye witnesses to the fact that Jesus had been resurrected. The arguments presented here against this stated requirement are without merit.
Being an eyewitness to Jesus' resurrection meant that they had seen Jesus after he rose from the grave. While there were many disciples, Jesus selected the original twelve specifically, and named them "apostles" as is stated in Luke 6:13.
"13 And when it was day, he called unto him his disciples: and of them he chose twelve, whom also he named apostles; 14 Simon, (whom he also named Peter,) and Andrew his brother, James and John, Philip and Bartholomew, 15 Matthew and Thomas, James the son of Alphaeus, and Simon called Zelotes,
16 And Judas the brother of James, and Judas Iscariot, which also was the traitor.
17 And he came down with them, and stood in the plain, and the company of his disciples, and a great multitude of people out of all Judaea and Jerusalem, and from the sea coast of Tyre and Sidon, which came to hear him, ..." (Luke 6:13-17, KJV)
They were distinguished from the other disciples and believers in Christ.
Peter was filled with the Holy Spirit, and listed the requirements during the selection of Matthias for the purpose of replacing Judas. The replacement had to have been a witness who saw Jesus after His death on the cross (Acts. 1:22).
We are not told what happened to Matthias, and Jesus did not specifically select him. But Paul definitely "saw" Jesus after His death on the cross. Jesus selected Paul specifically. Paul was in Jesus' presence, and heard His voice (Acts 22:6-9; 23:11), and witnessed the fact that Jesus was living and risen from the grave.
"18 And saw him saying unto me, Make haste, and get thee quickly out of Jerusalem: for they will not receive thy testimony concerning me." (Acts 22:18, KJV)
Moreover, it must be considered that having lived in Jerusalem (Acts 22:3) Paul surely had been aware of Jesus' ministry before His death on the cross, and most likely had seen Him. As Paul's sister's son (nephew) warned Paul of the Jews plans to kill him (Acts 23:16) Paul's family were living in Jerusalem. As violently opposed to Jesus' ministry as Paul had been (Acts 9:1-2), he certainly knew of Jesus and his death on the cross. Paul fulfilled all of the requirements Peter listed in Acts 1:21-22.
Paul's statements in the letters recommending fellow workers, calling them brothers and "son" does not confer the select appointment from Christ of apostleship upon any of them. He called Timothy his son in the faith (1 Tim 1:2). That does not make Timothy an apostle.
Paul called Titus his brother (2 Cor. 2:13), his partner and fellow helper (2 Cor. 8:23) and his own son after the common faith (Titus 1:4). Those statements do not raise Titus to the level of an apostle. Titus was a Greek, not a Jew (Gal. 2:3). Jesus' appointments for apostles were all Jews.
Further, listing the hierarchy of the roles / functions of the workers in 1 Cor. 12:28 places the apostles in the highest authority of the workers for the gospel of Christ. It is a listing in order of authority, and does not mean that any can seek to be an apostle.
Paul exhorted them to seek the greater gift, which he explained in the next vs. in 1 Cor. 13:1 to be charity, or love. The greater gift was not apostleship, nor any of the other functions Paul had listed in 1 Cor. 12:28.
The attempt here to allow for others than those Jesus appointed to be apostles as though the function was ordinary or attainable by all is not supported by the scriptures. This also rules out any having been "selected" by Christ past the 1st century AD as no one after the 1st century AD had any claim to have seen Jesus during His earthly ministry.