Yes, Yahya 'bin Saeed al-Qattan Abu Zakariya was a "Thiqah", with the testimony of the scholars of the Sunni denomination of Islam, and with the testimony of the people that lived with him. But, with the testimony of our scholars, he was a Nasibi, for the traditions that he narrated.
Ayatollah Muhammad al-Sanad said:
"This Yahya is from the Nawasib."
وَيَحْيَىٰ هَذَا مِنْ النُوَاصِب
and he said:
"Yahya's enmity and hate for the Ahlulbayt (peace and blessings be upon them) and his hatred towards them, and he slandered tens of narrators because they were 'Sh'ii or because they have the sentiment (passion) of 'Tashayyu, and who is this Yahya bin Saeed, in origin, and descent, so you see him as a great scholar?"
عَدَاوَة يَحْيَىٰ بِنَ سَعِيد لِأهلُ البَيت صَلَوٰاتُ الله وَسَلَامُهُ عَلَيْهُم وَحِقدَهُ عَلَيْهُم، وَقَد طَعَنَ فِي عَشَرَاتُ الرِواة لِأنَهُم يَتَشَيَعُون أو لِأنَ عِندَهُم هَوَىٰ التَشَيُع، وَمَنْ عَسَىٰ أن يَكُون يَحْيَىٰ بنُ سَعِيد أصلاً وَفصلاً وَحَسَبَاً وَنسباً كَيّ تَعرِفَ النُجُوم الزَهِرَات بِه؟
- Page 317, al-Ijtihad wal-Taqlid fi ilm al-Rijal"
And it could be that al-Najashi and al-Hili (رَضيَّ الله عَنُهم) had mistaken him for someone else, or that they thought he was a good man from the testimonies of the scholars of the Sunni school of thought that said he was a "Thiqah", because as you know, it's known that al-Hili (رَضيَّ الله عَنه) had implemented things from other schools of thought to the Sh'ii school of thought, so it isn't impossible that he implemented this Nasibi as well. Only Allah knows. But he's a Nasibi with the consensuses of our school of thought's scholars, so don't take narrations from him. And at the end of the day, he only narrated a few traditions, that no Sh'ii person would take in mind!