First, an arranged marriage is the same as a forced marriage. Even today among for instance the Haredim in ISrael who do arranged marriages,all the parties consent, and usually with joy and gratitude. They have a high rate of marriage success.
Second, please take into account that Jesus chose two different words, reflected in the two different words in the Greek, porneia and moicheia. Moicheia is incontestably adultery. Porneia is not. It’s reasonable to think that if He meant they were the same thing, He would have used the same word.
Third, consider the overall message Jesus is conveying here: it is that what GOD has joined together, no man is to put asunder. The core message here clearly goes way past the contemporary Hillel-Shammai debate. If Jesus had been merely agreeing with Shammai, his listeners would not have been flabbergasted, as they clearly were in the Gospel. accounts,
I don’t disagree with what you’ve posted, but this does not line up with RCC teachings on annulments and “unlawful” marriages.