  We homogeneously analyse $\sim 3.2\times 10^5$ photometric measurements for
$\sim 1100$ transit lightcurves belonging to $17$ exoplanet hosts. The
photometric data cover $16$ years 2004--2019 and include amateur and
professional observations. Old archival lightcurves were reprocessed using
up-to-date exoplanetary parameters and empirically debiased limb-darkening
models. We also derive self-consistent transit and radial-velocity fits for
$13$ targets. We confirm the nonlinear TTV trend in the WASP-12 data at a high
significance, and with a consistent magnitude. However, Doppler data reveal
hints of a radial acceleration about $(-7.5\pm 2.2)$~m/s/yr, indicating the
presence of unseen distant companions, and suggesting that roughly $10$ per
cent of the observed TTV was induced via the light-travel (or Roemer) effect.
For WASP-4, a similar TTV trend suspected after the recent TESS observations
appears controversial and model-dependent. It is not supported by our
homogeneus TTV sample, including $10$ ground-based EXPANSION lightcurves
obtained in 2018 simultaneously with TESS. Even if the TTV trend itself does
exist in WASP-4, its magnitude and tidal nature are uncertain. Doppler data
cannot entirely rule out the Roemer effect induced by possible distant
companions.
