I get most of my Duggar news from Reddit but I feel like they're skirting arpund a lot of what they are thinking. What do people think is going on with evicting the Caldwells from the house, given that people think the victim is one of her sisters? I dont get what people think is going on. It seems crazy that kendra was happy on the phone call about her family being evicted. Does she need the house for money, for somewhere to live? Or is it about a break with her family? But why would she be happy about it if it involves her sister being molested by her husband

help me out pls!
Total speculation but I'd guess that Kendra and Joe see it as a total betrayal. These issues are supposed to be handled 'in house' in their religion (cult) aka covered up without police or CPS involvement, legal proceedings or public scrutiny. See Josh's teenage crimes and lack of accountability before he was eventually apprehended on different charges as an adult.
As others have said they don't really care that Joe's committed a revolting crime or anything about the victim. They just want it brushed under the carpet, a quick private apology issued and instant forgiveness.
The fact that Kendra's dad a) reported it to authorities (a big no-no) and b) extracted a confession from Joe in a recorded phone conversation (?) would be considered completely outrageous.
I'm getting a strong impression that Kendra considers herself a Duggar by marriage and is honouring her husband/headship by taking his family's side and heeding their advice. I don't know about the 'leave and cleave' upon marriage thing in their culture. For the most part JB seems to lose daughters and gain daughters-in-law. Jessa is an exception (they don't seem that tight with Ben's family for example) and I don't know about Joy. She seems to lead more of a Forsyth lifestyle but is still close with her own family. Jinger and Jana live away and are more under their husbands' umbrellas rather than JB's. Jill we know about, I think she'd still be very close with her parents and siblings had there not been the falling out. It's been discussed that she misses their big fundie family dynamic and is gradually easing back in via her mom and sisters but I don't know how that's received in her marriage.
The daughters-in-law submit to their husbands and all the Duggar guys still have strong ties and dependency on JB - employment, church, money, connections. Some of the DILs have relocated to live in NW AR so there's a geographic distance with their own families. None of the married Duggar sons have moved away from JB's sphere of influence unlike some of the Bates sons.
All of this is exacerbated by Joe and Kendra allowing the Caldwells to live in their house/on their land and probably feeling like they did her family a massive favour/have supported them financially for years. Not that that excuses what Joe's alleged/has confessed to doing.
I read on Reddit that the Caldwells purchased an adjacent plot of land (or were gifted it by J&K) and were supposed to build their own modest home on it and move in within 3 or 5 years. That didn't happen and they've made no move to vacate Joe and Kendra's property. There seems to be other historic bad blood with JB dating from COVID times: Mr Caldwell wanting keep the church he pastored open during lockdown, JB saying no for PR reasons, JB being right for once, Mr Caldwell doing it anyway resulting in the Caldwells being evicted from the property they were living in, owned by JB. There's also a rumour that JB wanted Kendra's next youngest sister Lauren (they look alike) as a bride for another son. But due to the Josh scandal Mr Caldwell declined which didn't go down well with JB who's used to getting his own way and had by that time done the Caldwells quite a lot of favours by relocating them to NW AR, housing them, installing Mr Caldwell as a pastor at his church and probably other financial incentives.
I don't think the Caldwells are above reproach, it sounds like they've been relying too much on Joe and Kendra financially and for who knows what else, and trying to benefit from Duggar proximity. While continuing to pop out children they couldn't afford. But so far they appear to have the moral high ground in this situation (I don't know if they have skeletons themselves, fundamentalism appears riddled with it). Their youngest children are of an age that both parents could get out and work. They have a free childminder in their adult stay-at-home unmarried daughter Lauren. Obviously women aren't expected to work in their culture but with two incomes they ought to be able to support themselves.
I'm sure everything has been compounded by Kendra copping charges herself.