Should I be concerned about concrete/cement sealer fumes?
Get a canary if it dies you know you should not be there.
Seriously, some mixtures do release VOC’s (volatile organic compounds), and these are not good for you.
The adhesive in the pebble stone overlay I have used in the past is approved for indoor use but it stinks bad.
It takes about a week to off-gas and this is most likely what you are smelling. Keeping a positive pressure so the air is pushed out from that side of the house will help. I believe the stuff I used sets in 3-4 hours and is cured in 24 hours but stinks for about a week (it gets better as time goes on)
I would ask the contractor for the name of the bonding agent they are required by law to provide the safety data sheet used to be called MSDS (material safety datasheet) you should be able to find a document that provides any known hazards like VOC’s the hazard limit and all the information on the chemicals.
I would say if they were working without respirators you will be fine but I worked without respiratory protection around both asbestos and lead for ~30 years before the current recommendations for masking and isolation were made.