Playing notes doesn't play it actually long

Score got last saved with 3.5.2 -> time to update to 3.6.2. Even if that doesn't solve this particular problem.

Anyway, I believe you're hearing the effect of the marcatos you aplied to these notes, which indeed shortens notes to 67%, see the instruments definitions, esp. the gateTime:

      <Articulation name="marcato">
            <velocity>120</velocity>
            <gateTime>67</gateTime>
      </Articulation>
 <xml>
 
The effect you probably want is:
<xml>
      <Articulation name="marcatoTenuto">
            <velocity>120</velocity>
            <gateTime>100</gateTime>
      </Articulation>
 

so use a Marcato-Tenuto instead.
Or use the Piano Roll Editor to lengthen those notes to 100%