Hi @RAFAEL ASSAYAG ,
Good Day !
just now I gone through your OAP file, You have doe a fantastic job.
Here below are some changes I'm sharing
1) Use Data action for SQL so that Check-In date ad Check-out date you can pass it from main module other than using core module which you had created GetAvailableRoom server action passing input parameters.

2) By just using refreshing Data action you can achieve your Requirement.

Please check the attached OML.
Please check the below link.
Link : DMEO Link
I hope this helps ad you will get a proper solution.
- Palle Vijay Bhaskar Reddy