The low bat detector still uses quite some power. A simpler version would use the 5 V regulator as a "reference" and than compare something like 45% of the input voltage to the 2.5 V. For this one could use an OP-amp (e.g. use MCP6002 together with the virtual ground).
I would still want a footprint for a ceramic capacitor in front of the regulator. Low impedance at the input side is usually helping the regulators.
The capacitors C8 and C9 should be low leakage types - so more like film types that are usually easier to get as THT parts. Beside leakage, also the dielectric absorbtion from X7R or similar capacitors would be an issue. If SMD is really needed this would be C0G types and these would likely need a larger footprint, maybe a little less capacitance. C10 is a little less critical, by I would still prefer a film type here, just to be on the safe side (X7R may need a little more settling time).
The bias compensation may want an extra footprint for an alternative to R23, but to the negative side. The bias can have either sign.
The resistors R3,R4,R5 may want a larger foot-print (at least 0805 ideally even more), so they can better withstand transient voltages.
Ideally the meter would have a way to indicate clipping, e.g. from mains hum. So some kind of comparators to check if the output exceeds some +-2.3 V at any time. A slow DMM may not notice this.