which hebrew fonts are chosen? Changed after some private truetype fonts were added

[Uwe Brauer]

Hi

This seems bizarre. I am running Ubuntu 14.04 and GNU emacs 26.0.50.1.
I have set the default font to 
(custom-set-faces
 ;; custom-set-faces was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 '(default ((t (:family "DejaVu Sans Mono" :foundry "unknown" :slant
 normal :weight normal :height 143 :width normal)))))

And when I switch to hebrew input the fonts which is used looks quite
well in fact it is

,----
|              position: 21 of 27 (74%), column: 3
|             character: ם‎ (displayed as ם‎) (codepoint 1501, #o2735, #x5dd)
|     preferred charset: unicode (Unicode (ISO10646))
| code point in charset: 0x05DD
|                script: hebrew
|                syntax: w      which means: word
|              category: .:Base, R:Right-to-left (strong)
|              to input: type "C-x 8 RET 5dd" or "C-x 8 RET HEBREW LETTER FINAL 
MEM"
|           buffer code: #xD7 #x9D
|             file code: #xD7 #x9D (encoded by coding system utf-8-unix)
|               display: by this font (glyph code)
|     xft:-unknown-DejaVu Sans-normal-normal-normal-*-19-*-*-*-*-0-iso10646-1 
(#x533)
| 
| Character code properties: customize what to show
|   name: HEBREW LETTER FINAL MEM
|   general-category: Lo (Letter, Other)
|   decomposition: (1501) ('ם')
| 
| There are text properties here:
|   fontified            t
`----

However I just installed some private true type font

into /usr/share/fonts/private
basically some hebrew fonts based on my handwriting.
Run sudo fc-cache -f
restart emacs but *then*
the font used for hebrew is my just installed handwritten ttf?
,----
|              position: 21 of 22 (91%), column: 3
|             character: ם‎ (displayed as ם‎) (codepoint 1501, #o2735, #x5dd)
|     preferred charset: unicode (Unicode (ISO10646))
| code point in charset: 0x05DD
|                script: hebrew
|                syntax: w      which means: word
|              category: .:Base, R:Right-to-left (strong)
|              to input: type "M" with hebrew-phonetic-qwerty input method
|           buffer code: #xD7 #x9D
|             file code: #xD7 #x9D (encoded by coding system utf-8-unix)
|               display: by this font (glyph code)
|     xft:-unknown-uwehebhand-normal-normal-normal-*-19-*-*-*-*-0-iso10646-1 
(#x68)
| 
| Character code properties: customize what to show
|   name: HEBREW LETTER FINAL MEM
|   general-category: Lo (Letter, Other)
|   decomposition: (1501) ('ם')
| 
| There are text properties here:
|   fontified            t
`----

What on earth did happen?

How can I avoid this behavior?

Thanks

Uwe Brauer